Coterra Energy (CTRA) 10-K26 Feb 212020 FY Annual reportFinancial data

Company Profile

Cover Page

Cover Page - USD ($) $ in Billions	12 Months Ended
Cover Page - USD ($) $ in Billions	Dec. 31, 2020	Feb. 22, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2020
Entity File Number	1-10447
Entity Registrant Name	CABOT OIL & GAS CORPORATION
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	04-3072771
Entity Address, Address Line One	Three Memorial City Plaza
Entity Address, Address Line Two	840 Gessner Road
Entity Address, Address Line Three	Suite 1400
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77024
City Area Code	281
Local Phone Number	589-4600
Title of 12(b) Security	Common Stock, par value $0.10 per share
Trading Symbol	COG
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 6.7
Entity Common Stock, Shares Outstanding		399,419,748
Entity Central Index Key	0000858470
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false
Documents Incorporated by Reference	Portions of the Proxy Statement for the Annual Meeting of Stockholders to be held April 29, 2021 are incorporated by reference into Part III of this report.

CONSOLIDATED BALANCE SHEET

CONSOLIDATED BALANCE SHEET - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 140,113	$ 200,227
Restricted cash	11,578	13,556
Accounts receivable, net	214,724	209,023
Income taxes receivable	6,171	129,795
Inventories	15,270	13,932
Derivative instruments	26,209	31
Other current assets	1,650	1,684
Total current assets	415,715	568,248
Properties and equipment, net (Successful efforts method)	4,044,606	3,855,706
Other assets	63,211	63,291
TOTAL ASSETS	4,523,532	4,487,245
Current liabilities
Accounts payable	162,081	189,811
Current portion of long-term debt	188,000	87,000
Accrued liabilities	22,374	31,290
Interest payable	17,771	19,933
Total current liabilities	390,226	328,034
Long-term debt, net	945,924	1,133,025
Deferred income taxes	774,195	702,104
Asset retirement obligations	85,489	71,598
Postretirement benefits	30,713	32,713
Other liabilities	81,278	68,284
Total liabilities	2,307,825	2,335,758
Commitments and contingencies
Stockholders' equity
Common stock: Authorized — 960,000,000 shares of $0.10 par value in 2020 and 2019, respectively and Issued — 476,881,991 shares and 476,881,991 shares in 2020 and 2019, respectively	47,783	47,688
Additional paid-in capital	1,804,354	1,782,427
Retained earnings	2,184,352	2,143,213
Accumulated other comprehensive income	2,419	1,360
Treasury Stock, Value	(1,823,201)	(1,823,201)
Total stockholders' equity	2,215,707	2,151,487
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 4,523,532	$ 4,487,245

CONSOLIDATED BALANCE SHEET (Par

CONSOLIDATED BALANCE SHEET (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Common stock, authorized (in shares)	960,000,000	960,000,000
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, issued (in shares)	477,828,813	476,881,991
Treasury stock (in shares)	78,957,318	78,957,318

CONSOLIDATED STATEMENT OF OPERA

CONSOLIDATED STATEMENT OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
OPERATING REVENUES
Total revenues from contracts with customers	$ 1,405,220	$ 1,985,469	$ 2,143,716
Gain on derivative instruments	61,404	80,808	44,432
Total operating revenues	1,466,624	2,066,277	2,188,148
OPERATING EXPENSES
Direct operations	73,403	76,958	69,646
Taxes other than income	14,380	17,053	22,642
Exploration	15,419	20,270	113,820
Depreciation, depletion and amortization	390,903	405,733	417,479
General and administrative	105,391	94,870	96,641
TOTAL OPERATING EXPENSES	1,170,598	1,189,561	1,401,157
(Loss) earnings on equity method investments	(59)	80,496	1,137
(Loss) gain on sale of assets	(491)	(1,462)	(16,327)
INCOME FROM OPERATIONS	295,476	955,750	771,801
Interest expense, net	54,124	54,952	73,201
Other expense	229	574	463
Income before income taxes	241,123	900,224	698,137
Income tax expense	40,594	219,154	141,094
NET INCOME	$ 200,529	$ 681,070	$ 557,043
Earnings per share
Basic (in dollars per share)	$ 0.50	$ 1.64	$ 1.25
Diluted (in dollars per share)	$ 0.50	$ 1.63	$ 1.24
Weighted-average common shares outstanding
Basic (in shares)	398,521	415,514	445,538
Diluted (in shares)	400,522	417,451	447,568
Natural gas
OPERATING REVENUES
Total revenues from contracts with customers	$ 1,404,989	$ 1,985,240	$ 1,881,150
Crude oil and condensate
OPERATING REVENUES
Total revenues from contracts with customers	0	0	48,722
Brokered natural gas
OPERATING REVENUES
Total revenues from contracts with customers	0	0	209,530
OPERATING EXPENSES
Operating expenses	0	0	184,198
Other
OPERATING REVENUES
Total revenues from contracts with customers	231	229	4,314
Transportation and gathering
OPERATING EXPENSES
Operating expenses	$ 571,102	$ 574,677	$ 496,731

CONSOLIDATED STATEMENT OF COMPR

CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income		$ 200,529	$ 681,070	$ 557,043
Postretirement benefits:
Net actuarial gain (loss)	[1]	1,634	(2,530)	2,461
Amortization of prior service cost	[2]	(547)	(547)	(547)
Amortization of net loss	[3]	(28)	0	0
Cumulative effect of adoption of ASU 2018-02 reclassified to retained earnings		0	0	446
Total other comprehensive income		1,059	(3,077)	2,360
Comprehensive income		$ 201,588	$ 677,993	$ 559,403

[1]	Net of income taxes of $(484), $749 and $(704) for the year ended December 31, 2020, 2019 and 2018, respectively.
[2]	Net of income taxes of $162, $162 and $162 for the year ended December 31, 2020, 2019 and 2018, respectively.
[3]	Net of income taxes of $8 for the year ended December 31, 2020.

CONSOLIDATED STATEMENT OF COM_2

CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Postretirement benefits:
Net actuarial gain (loss), income taxes	$ (484)	$ 749	$ (704)
Amortization of prior service cost, income taxes	162	$ 162	$ 162
Prior service credit, income taxes	$ 8

CONSOLIDATED STATEMENT OF CASH

CONSOLIDATED STATEMENT OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 200,529	$ 681,070	$ 557,043
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	390,903	405,733	417,479
Deferred income tax expense	71,777	244,418	229,603
Loss on sale of assets	491	1,462	16,327
Exploratory dry hole cost	3,632	2,236	97,741
Gain on derivative instruments	(61,404)	(80,808)	(44,432)
Net cash received (paid) in settlement of derivative instruments	35,218	138,450	(41,631)
Loss (earnings) on equity method investments	59	(80,496)	(1,137)
Distribution of earnings from equity method investments	0	15,725	1,296
Amortization of debt issuance costs	2,961	3,966	4,631
Stock-based compensation and other	40,796	29,009	31,443
Changes in assets and liabilities:
Accounts receivable, net	(5,700)	153,379	(146,921)
Income taxes	123,624	(13,514)	(59,616)
Inventories	(1,981)	(2,856)	(3,927)
Other current assets	34	180	934
Accounts payable and accrued liabilities	(30,040)	(30,176)	30,468
Interest payable	(2,162)	(166)	(7,477)
Other assets and liabilities	9,498	(21,821)	23,079
Net cash provided by operating activities	778,235	1,445,791	1,104,903
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(575,847)	(788,368)	(894,470)
Proceeds from sale of assets	828	2,600	678,350
Investment in equity method investments	(35)	(9,338)	(77,263)
Distribution of investment from equity method investments	0	1,728	0
Proceeds from sale of equity method investments	(9,424)
Proceeds from sale of equity method investments		249,463	0
Net cash used in investing activities	(584,478)	(543,915)	(293,383)
CASH FLOWS FROM FINANCING ACTIVITIES
Borrowings from debt	196,000	95,000	158,000
Repayments of debt	(283,000)	(102,000)	(455,000)
Treasury stock repurchases	0	(519,863)	(872,761)
Dividends paid	(159,390)	(145,515)	(111,369)
Tax withholding on vesting of stock awards	(9,459)	(10,590)	(8,150)
Capitalized debt issuance costs	0	(7,412)	0
Net cash used in financing activities	(255,849)	(690,380)	(1,289,280)
Net (decrease) increase in cash, cash equivalents and restricted cash	(62,092)	211,496	(477,760)
Cash, cash equivalents and restricted cash, beginning of period	213,783	2,287	480,047
Cash, cash equivalents and restricted cash, end of period	$ 151,691	$ 213,783	$ 2,287

CONSOLIDATED STATEMENT OF STOCK

CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Cumulative impact from accounting change	Common Shares	Treasury Stock	Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Retained EarningsCumulative impact from accounting change
Balance (in shares) at Dec. 31, 2017			475,547,000	14,936,000
Balance at beginning of period at Dec. 31, 2017	$ 2,523,905	$ (446)	$ 47,555	$ (430,576)	$ 1,742,419	$ 2,077	$ 1,162,430	$ (446)
Increase (Decrease) in Stockholders' Equity
Net income	557,043						557,043
Exercise of stock appreciation rights (in shares)			9,000
Exercise of stock appreciation rights	0		$ 1		(1)
Stock amortization and vesting (in shares)			539,000
Stock amortization and vesting	20,778		$ 54		20,724
Purchase of treasury stock (in shares)				38,474,000
Purchase of treasury stock	(904,112)			$ (904,112)
Cash dividends	(111,369)						(111,369)
Other comprehensive income	2,360					2,360
Balance (in shares) at Dec. 31, 2018			476,095,000	53,410,000
Balance at end of period at Dec. 31, 2018	2,088,159		$ 47,610	$ (1,334,688)	1,763,142	4,437	1,607,658
Increase (Decrease) in Stockholders' Equity
Net income	681,070						681,070
Stock amortization and vesting (in shares)			787,000
Stock amortization and vesting	19,363		$ 78		19,285
Purchase of treasury stock (in shares)				25,547,000
Purchase of treasury stock	(488,513)			$ (488,513)
Cash dividends	(145,515)						(145,515)
Other comprehensive income	(3,077)					(3,077)
Balance (in shares) at Dec. 31, 2019			476,882,000	78,957,000
Balance at end of period at Dec. 31, 2019	2,151,487		$ 47,688	$ (1,823,201)	1,782,427	1,360	2,143,213
Increase (Decrease) in Stockholders' Equity
Net income	200,529						200,529
Stock amortization and vesting (in shares)			947,000
Stock amortization and vesting	22,022		$ 95		21,927
Cash dividends	(159,390)						(159,390)
Other comprehensive income	1,059					1,059
Balance (in shares) at Dec. 31, 2020			477,829,000	78,957,000
Balance at end of period at Dec. 31, 2020	$ 2,215,707		$ 47,783	$ (1,823,201)	$ 1,804,354	$ 2,419	$ 2,184,352

CONSOLIDATED STATEMENT OF STO_2

CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Stockholders' Equity [Abstract]
Cash dividends, per share (in dollars per share)	$ 0.40	$ 0.35	$ 0.25

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	12 Months Ended
Supplemental Cash Flow Information	Dec. 31, 2020
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information Year Ended December 31, (In thousands) 2020 2019 2018 Cash paid for interest and income taxes Interest $ 57,043 $ 57,475 $ 80,069 Income taxes 10,964 7,808 4,635 Cash, cash equivalents and restricted cash, included in the Consolidated Statement of Cash Flow, is comprised of the following: December 31, (In thousands) 2020 2019 Cash and cash equivalents $ 140,113 $ 200,227 Restricted cash 11,578 13,556 $ 151,691 $ 213,783

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
Summary of Significant Accounting Policies	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation and Nature of Operations Cabot Oil & Gas Corporation and its subsidiaries (the Company) are engaged in the development, exploitation, exploration, production and marketing of natural gas exclusively within the continental United States. The Company's exploration and development activities are concentrated in areas with known hydrocarbon resources, which are conducive to multi-well, repeatable drilling programs. The Company operates in one segment, natural gas development, exploitation, exploration and production. The Company's oil and gas properties are managed as a whole rather than through discrete operating segments or business units. Operational information is tracked by geographic area; however, financial performance is assessed as a single enterprise and not on a geographic basis. Allocation of resources is made on a project basis across the Company's entire portfolio without regard to geographic areas. The consolidated financial statements include the accounts of the Company and its subsidiaries after eliminating all significant intercompany balances and transactions. Certain reclassifications have been made to prior year statements to conform with the current year presentation. These reclassifications have no impact on previously reported stockholders' equity, net income or cash flows. Recently Adopted Accounting Pronouncements Financial Instruments: Credit Losses. In June 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2016-13, Financial Instruments: Credit Losses, which replaces the incurred loss impairment methodology used for certain financial instruments with a methodology that reflects current expected credit losses (CECL). ASU No. 2016-13, along with subsequently issued codification improvements, was effective for the Company on January 1, 2020, and was applied using a modified retrospective approach. The Company's historical credit losses have not been material, and future expected credit losses under the CECL model are not expected to be material. The adoption of ASU No. 2016-13 did not have a material effect on the Company's financial position, results of operations or cash flows; however, it modified certain disclosure requirements, which were not material. Fair Value Measurements. In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement, which modifies the disclosure requirements by adding, removing and modifying certain required disclosures for fair value measurements for assets and liabilities disclosed within the fair value hierarchy. The Company adopted ASU No. 2018-13 effective January 1, 2020. The adoption of ASU No. 2018-13 did not have any effect on the Company's financial position, results of operations or cash flows; however, it modified certain disclosure requirements, which were not material. Defined Benefit Plans. In August 2018, the FASB issued ASU No. 2018-14, Compensation - Retirement Benefits - Defined Benefit Plans - General (Subtopic 715-20), which modifies the disclosure requirements by adding, removing and clarifying certain required disclosures for defined benefit plans. The Company adopted ASU No. 2018-14 during the fiscal year ended December 31, 2020. The adoption of ASU No. 2018-14 did not have any effect on the Company's financial positions, results of operations or cash flows; however, it modified certain disclosures, which were not material. Significant Accounting Policies Cash and Cash Equivalents The Company considers all highly liquid short-term investments with a maturity of three months or less and deposits in money market funds that are readily convertible to cash to be cash equivalents. Cash and cash equivalents were primarily concentrated in one financial institution at December 31, 2020. The Company periodically assesses the financial condition of its financial institutions and considers any possible credit risk to be minimal. From time to time, the Company may be in the position of a book overdraft in which outstanding checks exceed cash and cash equivalents. The Company classifies book overdrafts in accounts payable in the Consolidated Balance Sheet, and classifies the change in accounts payable associated with book overdrafts as an operating activity in the Consolidated Statement of Cash Flows. There was no book overdraft within accounts payable as of December 31, 2020 and 2019. Restricted Cash. Restricted cash includes cash that is legally or contractually restricted as to withdrawal or usage. As of December 31, 2020 and 2019, the restricted cash balance of $11.6 million and $13.6 million, respectively, includes cash deposited in escrow accounts related to the sale of the Company's equity investment in Meade Pipeline Co LLC (Meade). Allowance for Doubtful Accounts The Company records an allowance for doubtful accounts based on the Company's estimate of future expected credit losses on outstanding receivables. Inventories Inventories are comprised of tubular goods and well equipment and are carried at average cost. Equity Method Investments The Company accounts for its investments in entities over which the Company has significant influence, but not control, using the equity method of accounting. Under the equity method of accounting, the Company increases its investment for contributions made and records its proportionate share of net earnings, declared dividends and partnership distributions based on the most recently available financial statements of the investee. The Company records the activity for its equity method investments on a one month lag. In addition, the Company evaluates its equity method investments for potential impairment whenever events or changes in circumstances indicate that there is a decline in the value of the investment. Properties and Equipment The Company uses the successful efforts method of accounting for oil and gas producing activities. Under this method, acquisition costs for proved and unproved properties are capitalized when incurred. Exploration costs, including geological and geophysical costs, the costs of carrying and retaining unproved properties and exploratory dry hole drilling costs, are expensed. Development costs, including the costs to drill and equip development wells and successful exploratory drilling costs to locate proved reserves are capitalized. Exploratory drilling costs are capitalized when incurred pending the determination of whether a well has found proved reserves. The determination is based on a process which relies on interpretations of available geologic, geophysical, and engineering data. If a well is determined to be successful, the capitalized drilling costs will be reclassified as part of the cost of the well. If a well is determined to be unsuccessful, the capitalized drilling costs will be charged to exploration expense in the Consolidated Statement of Operations in the period the determination is made. If an exploratory well requires a major capital expenditure before production can begin, the cost of drilling the exploratory well will continue to be carried as an asset pending determination of whether reserves have been found only as long as: (i) the well has found a sufficient quantity of reserves to justify its completion as a producing well if the required capital expenditure is made and (ii) drilling of an additional exploratory well is under way or firmly planned for the near future. If drilling in the area is not under way or firmly planned, or if the well has not found a commercially producible quantity of reserves, the exploratory well is assumed to be impaired and its costs are charged to exploration expense. Development costs of proved oil and gas properties, including estimated dismantlement, restoration and abandonment costs and acquisition costs, are depreciated and depleted on a field basis by the units-of-production method using proved developed and proved reserves, respectively. Buildings are depreciated on a straight-line basis over 25 to 40 years. Certain other assets are depreciated on a straight-line basis over 3 to 25 years. Costs of sold or abandoned properties that make up a part of an amortization base (partial field) remain in the amortization base if the units-of-production rate is not significantly affected. If significant, a gain or loss, if any, is recognized and the sold or abandoned properties are retired. A gain or loss, if any, is also recognized when a group of proved properties (entire field) that make up the amortization base has been retired, abandoned or sold. The Company evaluates its proved oil and gas properties for impairment whenever events or changes in circumstances indicate an asset's carrying amount may not be recoverable. The Company compares expected undiscounted future cash flows to the net book value of the asset. If the future undiscounted expected cash flows, based on estimates of future commodity prices, operating costs and anticipated production from proved reserves and risk-adjusted probable and possible reserves, are lower than the net book value of the asset, the capitalized cost is reduced to fair value. Commodity pricing is estimated by using a combination of assumptions management uses in its budgeting and forecasting process as well as historical and current prices adjusted for geographical location and quality differentials, as well as other factors that management believes will impact realizable prices. Fair value is calculated by discounting the future cash flows. The discount factor used is based on rates utilized by market participants that are commensurate with the risks inherent in the development and production of the underlying natural gas and oil. Unproved oil and gas properties are assessed periodically for impairment on an aggregate basis through periodic updates to the Company's undeveloped acreage amortization based on past drilling and exploration experience, the Company's expectation of converting leases to held by production and average property lives. Average property lives are determined on a geographical basis and based on the estimated life of unproved property leasehold rights. During 2020, 2019 and 2018, amortization associated with the Company's unproved properties was $8.2 million, $32.6 million and $82.3 million, respectively, and is included in depreciation, depletion, and amortization in the Consolidated Statement of Operations. Asset Retirement Obligations The Company records the fair value of a liability for an asset retirement obligation in the period in which it is incurred if a reasonable estimate of fair value can be made. The associated asset retirement cost is capitalized as part of the carrying amount of the long-lived asset. The asset retirement costs are depreciated using the units-of-production method. At December 31, 2020 and 2019, there were no assets legally restricted for purposes of settling asset retirement obligations. Additional retirement obligations increase the liability associated with new oil and gas wells and other facilities as these obligations are incurred. Accretion expense is included in depreciation, depletion and amortization expense in the Consolidated Statement of Operations. Derivative Instruments The Company enters into financial derivative contracts, primarily swaps, collars and basis swaps, to manage its exposure to price fluctuations on a portion of its anticipated future production volumes. The Company’s credit agreement restricts the ability of the Company to enter into commodity derivatives other than to hedge or mitigate risks to which the Company has actual or projected exposure or as permitted under the Company’s risk management policies and where such derivatives do not subject the Company to material speculative risks. All of the Company’s derivatives are used for risk management purposes and are not held for trading purposes. The Company has elected not to designate its financial derivative instruments as accounting hedges under the accounting guidance. The Company evaluates all of its physical purchase and sale contracts to determine if they meet the definition of a derivative. For contracts that meet the definition of a derivative, the Company may elect the normal purchase normal sale (NPNS) exception provided under the accounting guidance and account for the contract using the accrual method of accounting. Contracts that do not qualify for or for which the Company elects not to apply the NPNS exception are accounted for at fair value. All derivatives, except for derivatives that qualify for the NPNS exception, are recognized on the balance sheet and are measured at fair value. At the end of each quarterly period, these derivatives are marked to market. As a result, changes in the fair value of derivatives are recognized in operating revenues in gain (loss) on derivative instruments. The resulting cash flows are reported as cash flows from operating activities. Leases The Company determines if an arrangement is, or contains, a lease at inception based on whether that contract conveys the right to control the use of an identified asset in exchange for consideration for a period of time. Operating leases are included in operating lease right-of-use assets (ROU assets) and operating lease liabilities (current and non-current) in the Consolidated Balance Sheet. The Company did not have any finance leases at December 31, 2020 and 2019. ROU assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the leases. ROU assets and lease liabilities are recognized at the lease commencement date based on the present value of minimum lease payments over the lease term. Most leases do not provide an implicit interest rate; therefore, the Company used its incremental borrowing rate based on the information available at the inception date to determine the present value of the lease payments. Lease terms include options to extend the lease when it is reasonably certain that the Company will exercise that option. Lease cost for lease payments is recognized on a straight-line basis over the lease term. Certain leases have payment terms that vary based on the usage of the underlying assets. Variable lease payments are not included in ROU assets and lease liabilities. The Company has elected the following practical expedients in applying authoritative guidance on lease accounting: • For all operating leases, lease and non-lease components are accounted for as a single lease component. • Short-term leases (a lease that, at commencement, has a lease term of one year or less and does not contain a purchase option that the Company is reasonably certain to exercise) have not be recognized in ROU assets and lease liabilities. • Certain land easements in existence prior to January 1, 2019 were not reassessed under new accounting guidance. Fair Value of Assets and Liabilities The Company follows the authoritative accounting guidance for measuring fair value of assets and liabilities in its financial statements. Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). The Company utilizes market data or assumptions that market participants who are independent, knowledgeable and willing and able to transact would use in pricing the asset or liability, including assumptions about risk and the risks inherent in the inputs to the valuation technique. The Company is able to classify fair value balances based on the observability of these inputs. The authoritative guidance for fair value measurements establishes three levels of the fair value hierarchy, defined as follows: • Level 1: Unadjusted, quoted prices for identical assets or liabilities in active markets. • Level 2: Quoted prices in markets that are not considered to be active or financial instruments for which all significant inputs are observable, either directly or indirectly for substantially the full term of the asset or liability. • Level 3: Significant, unobservable inputs for use when little or no market data exists, requiring a significant degree of judgment. The hierarchy gives the highest priority to Level 1 measurements and the lowest priority to Level 3 measurements. Depending on the particular asset or liability, input availability can vary depending on factors such as product type, longevity of a product in the market and other particular transaction conditions. In some cases, certain inputs used to measure fair value may be categorized into different levels of the fair value hierarchy. For disclosure purposes under the accounting guidance, the lowest level that contains significant inputs used in the valuation should be chosen. Revenue Recognition The Company’s revenue is typically generated from contracts to sell natural gas produced from interests in oil and gas properties owned by the Company. These contracts generally require the Company to deliver a specific amount of a commodity per day for a specified number of days at a price that is either fixed or variable. The contracts specify a delivery point which represents the point at which control of the product is transferred to the customer. These contracts frequently meet the definition of a derivative under ASC 815, and are accounted for as derivatives unless the Company elects to treat them as normal sales as permitted under that guidance. The Company typically elects to treat contracts to sell oil and gas production as normal sales, which are then accounted for as contracts with customers. The Company has determined that these contracts represent multiple performance obligations which are satisfied when control of the commodity transfers to the customer, typically through the delivery of the specified commodity to a designated delivery point. Revenue is measured based on consideration specified in the contract with the customer, and excludes any amounts collected on behalf of third parties. The Company recognizes revenue in the amount that reflects the consideration it expects to be entitled to in exchange for transferring control of those goods to the customer. The contract consideration in the Company’s variable price contracts are typically allocated to specific performance obligations in the contract according to the price stated in the contract. Amounts allocated in the Company’s fixed price contracts are based on the standalone selling price of those products in the context of long-term, fixed price contracts, which generally approximates the contract price. Payment is generally received one or two months after the sale has occurred. Gain or loss on derivative instruments is outside the scope of the revenue recognition standard and is not considered revenue from contracts with customers under that guidance. The Company may use financial or physical contracts accounted for as derivatives as economic hedges to manage price risk associated with normal sales, or in limited cases may use them for contracts the Company intends to physically settle but do not meet all of the criteria to be treated as normal sales. Taxes assessed by a governmental authority that are both imposed on and concurrent with a specific revenue-producing transaction, and that are collected by the Company from a customer, are excluded from revenue. Producer Gas Imbalances. The Company applies the sales method of accounting for natural gas revenue. Under this method, revenues are recognized based on the actual volume of natural gas sold to purchasers. Natural gas production operations may include joint owners who take more or less than the production volumes entitled to them on certain properties. Production volume is monitored to minimize these natural gas imbalances. Under this method, a natural gas imbalance liability is recorded if the Company's excess takes of natural gas exceed its estimated remaining proved developed reserves for these properties at the actual price realized upon the gas sale. A receivable is recognized only to the extent an imbalance cannot be recouped from the reserves in the underlying properties. The Company’s aggregate imbalance positions at December 31, 2020 and 2019 were not material. Brokered Natural Gas. Revenues and expenses related to brokered natural gas are reported gross as part of operating revenues and operating expenses in accordance with applicable accounting standards. The Company buys and sells natural gas utilizing separate purchase and sale transactions whereby the Company or the counterparty obtains control of the natural gas purchased or sold. Practical Expedients. The Company makes use of certain practical expedients provided under the revenue standard, including the value of unsatisfied performance obligations are not disclosed for (i) contracts with an original expected length of one year or less, (ii) contracts for which the Company recognizes revenue at the amount to which the Company has the right to invoice, (iii) contracts with variable consideration which is allocated entirely to a wholly unsatisfied performance obligation and meets the variable allocation criteria in the standard and (iv) contracts that were not completed at transition. The Company has not adjusted the promised amount of consideration for the effects of a significant financing component if the Company expects, at contract inception, that the period between when the Company transfers a promised good or service to the customer and when the customer pays for that good or service will be one year or less. Income Taxes The Company follows the asset and liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are recorded for the estimated future tax consequences attributable to the differences between the financial carrying amounts of existing assets and liabilities and their respective tax basis. Deferred tax assets and liabilities are measured using the tax rate in effect for the year in which those temporary differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in the year of the enacted rate change. A valuation allowance is established to reduce deferred tax assets if it is more likely than not that the related tax benefits will not be realized. The Company follows the “equity first” approach when applying the limitation for certain executive compensation in excess of $1 million to future compensation. The limitation is first applied to stock-based compensation that vests in future tax years before considering cash compensation paid in a future period. Accordingly, the Company records a deferred tax asset for stock-based compensation expense recorded in the current period, and reverses the temporary difference in the future period, during which the stock-based compensation becomes deductible for tax purposes. The Company is required to make judgments, including estimating reserves for potential adverse outcomes regarding tax positions that the Company has taken. The Company accounts for uncertainty in income taxes using a recognition and measurement threshold for tax positions taken or expected to be taken in a tax return. The tax benefit from an uncertain tax position is recognized when it is more likely than not that the position will be sustained upon examination by taxing authorities based on technical merits of the position. The amount of the tax benefit recognized is the largest amount of the benefit that has a greater than 50 percent likelihood of being realized upon ultimate settlement. The effective tax rate and the tax basis of assets and liabilities reflect management's estimates of the ultimate outcome of various tax uncertainties. The Company recognizes accrued interest related to uncertain tax positions in interest expense and accrued penalties related to such positions in general and administrative expense in the Consolidated Statement of Operations. Stock-Based Compensation The Company accounts for stock-based compensation under the fair value method of accounting. Under this method, compensation cost is measured at the grant date for equity-classified awards and remeasured each reporting period for liability-classified awards based on the fair value of an award and is recognized over the service period, which is generally the vesting period. To calculate fair value, the Company uses a Monte Carlo valuation model based on the specific provisions of the award. Stock-based compensation cost for all types of awards is included in general and administrative expense in the Consolidated Statement of Operations. The Company records excess tax benefits and tax deficiencies on stock-based compensation in the income statement upon vesting of the respective awards. Excess tax benefits and tax deficiencies are included in cash flows from operating activities in the Consolidated Statement of Cash Flow. Cash paid by the Company when directly withholding shares from employee stock-based compensation awards for tax-withholding purposes are classified as financing activities in the Consolidated Statement of Cash Flow. Environmental Matters Environmental expenditures are expensed or capitalized, as appropriate, depending on their future economic benefit. Expenditures that relate to an existing condition caused by past operations, and that do not have future economic benefit are expensed. Liabilities related to future costs are recorded on an undiscounted basis when environmental assessments and/or remediation activities are probable and the costs can be reasonably estimated. Any insurance recoveries are recorded as assets when received. Credit and Concentration Risk Substantially all of the Company's accounts receivable result from the sale of natural gas to third parties in the oil and gas industry. This concentration of purchasers may impact the Company's overall credit risk, either positively or negatively, in that these entities may be similarly affected by changes in economic or other conditions. The Company does not anticipate any material impact on its financial results due to non-performance by the third parties. During the year ended December 31, 2020, three customers accounted for approximately 21 percent, 16 percent and 12 percent of the Company's total sales. During the year ended December 31, 2019, three customers accounted for approximately 17 percent, 16 percent and 16 percent of the Company's total sales. During the year ended December 31, 2018, two customers accounted for approximately 20 percent and 11 percent of the Company's total sales. The Company does not believe that the loss of any of these customers would have a material adverse effect on it because alternative customers are readily available. Use of Estimates In preparing financial statements, the Company follows accounting principles generally accepted in the United States. These principles require management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. The most significant estimates pertain to proved natural gas reserves and related cash flow estimates which are used to compute depreciation, depletion and amortization and impairments of proved oil and gas properties. Other significant estimates include natural gas revenues and expenses, fair value of derivative instruments, estimates of expenses related to legal, environmental and other contingencies, asset retirement obligations, postretirement obligations, stock-based compensation and deferred income taxes. Actual results could differ from those estimates.

Divestitures

Divestitures	12 Months Ended
Divestitures	Dec. 31, 2020
Business Combinations [Abstract]
Divestitures	Divestitures The Company recognized an aggregate net loss on sale of assets of $0.5 million, $1.5 million and $16.3 million for the years ended December 31, 2020, 2019 and 2018, respectively. In July 2018, the Company sold certain proved and unproved oil and gas properties in the Haynesville Shale to a third party for $30.0 million. The sales price included a $5.0 million deposit that was received in the fourth quarter of 2017. The Company recognized a gain on sale of oil and gas properties of $29.7 million. In February 2018, the Company sold certain proved and unproved oil and gas properties in the Eagle Ford Shale to an affiliate of Venado Oil & Gas LLC for $765.0 million. The sales price included a $76.5 million deposit that was received in the fourth quarter of 2017. During the fourth quarter of 2017, the Company recorded an impairment charge of $414.3 million associated with the proposed sale of these properties and upon closing recognized a loss on sale of oil and gas properties of $45.4 million.

Properties and Equipment, Net

Properties and Equipment, Net	12 Months Ended
Properties and Equipment, Net	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Properties and Equipment, Net	Properties and Equipment, Net Properties and equipment, net are comprised of the following: December 31, (In thousands) 2020 2019 Proved oil and gas properties $ 7,068,605 $ 6,508,443 Unproved oil and gas properties 49,829 133,475 Land, buildings and other equipment 92,566 104,700 7,211,000 6,746,618 Accumulated depreciation, depletion and amortization (3,166,394) (2,890,912) $ 4,044,606 $ 3,855,706 Capitalized Exploratory Well Costs The following table reflects the net changes in capitalized exploratory well costs: Year Ended December 31, (In thousands) 2020 2019 2018 Balance at beginning of period $ — $ — $ 19,511 Additions to capitalized exploratory well costs pending the — — — Reclassifications to wells, facilities, and equipment based on the — — — Capitalized exploratory well costs charged to expense — — (19,511) Balance at end of period $ — $ — $ — The following table provides an aging of capitalized exploratory well costs based on the date the drilling was completed: December 31, (In thousands) 2020 2019 2018 Capitalized exploratory well costs that have been capitalized for a period of one year or less $ — $ — $ — Capitalized exploratory well costs that have been capitalized for a period greater than one year — — — $ — $ — $ —

Equity Method Investments

Equity Method Investments	12 Months Ended
Equity Method Investments	Dec. 31, 2020
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments	Equity Method Investments Activity related to the Company's equity method investments is as follows: Constitution Meade Total Year Ended December 31, Year Ended December 31, Year Ended December 31, (In thousands) 2020 2019 2018 2020 2019 2018 2020 2019 2018 Balance at beginning of period $ — $ — $ 732 $ — $ 163,181 $ 85,345 $ — $ 163,181 $ 86,077 Contributions 35 725 500 — 8,613 76,763 35 9,338 77,263 Distributions — — — — (17,453) (1,296) — (17,453) (1,296) (Loss) earnings on equity method investments (35) (10,125) (1,232) (24) 90,621 2,369 (59) 80,496 1,137 Reclassification of accumulated losses (1) — 9,400 — — — — — 9,400 — Sale of investment — — — 24 (244,962) — 24 (244,962) — Balance at end of period $ — $ — $ — $ — $ — $ 163,181 $ — $ — $ 163,181 ______________________________________________________________________________ (1) Amount was included in accounts payable in the Consolidated Balance Sheet as of December 31, 2019. Constitution Pipeline Company, LLC In April 2012, the Company acquired a 25 percent equity interest in Constitution Pipeline Company, LLC (Constitution), which was formed to develop, construct and operate a 124-mile large diameter pipeline to transport natural gas from northeast Pennsylvania to both the New England and New York markets. Although Constitution received a certificate of public convenience and necessity from the Federal Energy and Regulatory Commission (FERC) to construct the proposed pipeline and obtained, among other approvals, a waiver of the water quality certification under Section 401 of the Clean Water Act for the New York portion of the project, the members of Constitution, following extensive evaluation and discussions regarding the diminished underlying economics for this project, have elected to not proceed with the project. As a result of this decision, as of December 31, 2019, the Company recorded a liability of $9.4 million which represents its estimated remaining obligations associated with the project. On February 10, 2020, the Company sold its 25 percent equity interest in Constitution to Williams Partners Operating LLC (Williams). The Company did not receive any proceeds and paid Williams $9.4 million that was previously accrued. Upon closing of the sale, the Company has no further obligations with respect to the project. Meade Pipeline Co LLC In February 2014, the Company acquired a 20 percent equity interest in Meade, which was formed to participate in the development and construction of the Central Penn Line, a 177-mile pipeline operated by Transcontinental Gas Pipe Line Company, LLC (Transco) that transports natural gas from Susquehanna County, Pennsylvania to an interconnect with Transco’s mainline in Lancaster County, Pennsylvania. The Central Penn Line is owned by Transco and Meade in proportion to their respective ownership percentages of approximately 61 percent and 39 percent, respectively. The Central Penn Line was placed into service on October 6, 2018.

Debt and Credit Agreements

Debt and Credit Agreements	12 Months Ended
Debt and Credit Agreements	Dec. 31, 2020
Debt Disclosure [Abstract]
Debt and Credit Agreements	Debt and Credit Agreements The Company's debt and credit agreements consisted of the following: December 31, (In thousands) 2020 2019 Total debt 6.51% weighted-average senior notes (1) $ 37,000 $ 124,000 5.58% weighted-average senior notes (2) 175,000 175,000 3.65% weighted-average senior notes (3) 925,000 925,000 Revolving credit facility — — Unamortized debt issuance costs (3,076) (3,975) $ 1,133,924 $ 1,220,025 _______________________________________________________________________________ (1) Includes $87.0 million of current portion of long-term debt at December 31, 2019, which the Company repaid in July 2020. (2) Includes $88.0 million of current portion of long-term debt at December 31, 2020, which the Company repaid in January 2021. (3) Includes $100.0 million of current portion of long-term debt at December 31, 2020 due in September 2021. The Company has debt maturities of $188.0 million due in 2021, $62.0 million due in 2023 and $575.0 million due in 2024 associated with its senior notes. In addition, the revolving credit facility matures in April 2024. No other tranches of debt are due within the next five years. At December 31, 2020, the Company was in compliance with all restrictive financial covenants for both its revolving credit facility and senior notes. Senior Notes The Company has various issuances of senior notes. Interest on each of the senior notes is payable semi-annually. Under the terms of the various senior note agreements, the Company may prepay all or any portion of the notes of each series on any date at a price equal to the principal amount thereof plus accrued and unpaid interest plus a make-whole premium. The Company's agreements provide that the Company maintain a minimum asset coverage ratio of 1.75 to 1.0 and a minimum annual coverage ratio of consolidated cash flow to interest expense for the trailing four quarters of 2.8 to 1.0. There are also various other covenants and events of default customarily found in such debt instruments. 6.51% Weighted-Average Senior Notes In July 2008, the Company issued $425.0 million of senior unsecured notes to a group of 41 institutional investors in a private placement. The notes have bullet maturities and were issued in three separate tranches as follows: Principal Term Maturity Coupon Tranche 1 $ 245,000,000 10 years July 2018 6.44 % Tranche 2 $ 100,000,000 12 years July 2020 6.54 % Tranche 3 $ 80,000,000 15 years July 2023 6.69 % In May 2016, the Company repurchased $8.0 million of Tranche 1, $13.0 million of Tranche 2 and $43.0 million of Tranche 3 for a total of $64.0 million for $68.3 million. As of December 31, 2020, the Company has repaid $388.0 million of aggregate principal amount associated with the 6.51% weighted-average senior notes. 5.58% Weighted-Average Senior Notes In December 2010, the Company issued $175.0 million of senior unsecured notes to a group of eight institutional investors in a private placement. The notes have bullet maturities and were issued in three separate tranches as follows: Principal Term Maturity Coupon Tranche 1 $ 88,000,000 10 years January 2021 5.42 % Tranche 2 $ 25,000,000 12 years January 2023 5.59 % Tranche 3 $ 62,000,000 15 years January 2026 5.80 % Subsequent Event. In January 2021, the Company repaid $88.0 million of maturities associated with its 5.58% weighted-average senior notes. 3.65% Weighted‑Average Senior Notes In September 2014, the Company issued $925.0 million of senior unsecured notes to a group of 24 institutional investors in a private placement. The notes have bullet maturities and were issued in three separate tranches as follows: Principal Term Maturity Date Coupon Tranche 1 $ 100,000,000 7 years September 2021 3.24 % Tranche 2 $ 575,000,000 10 years September 2024 3.67 % Tranche 3 $ 250,000,000 12 years September 2026 3.77 % Revolving Credit Agreement On April 22, 2019, the Company entered into a second amended and restated credit agreement (the revolving credit facility). The Company's revolving credit facility is unsecured and the borrowing base is redetermined annually on April 1. In addition, either the Company or the banks may request an interim redetermination twice a year or in connection with certain acquisitions or divestitures of oil and gas properties. The Company’s borrowing base and available commitments under the revolving credit facility were $3.2 billion and $1.5 billion, respectively. The maximum revolving credit available to the Company is the lesser of the available commitments or the difference of the borrowing base less outstanding senior notes. The Company's revolving credit facility matures in April 2024 and can be extended by one year upon the agreement of the Company and lenders holding at least 50 percent of the commitments under the revolving credit facility. Interest rates under the revolving credit facility are based on LIBOR or ABR indications, plus a margin which ranges from 150 to 225 basis points for LIBOR loans and from 50 to 125 basis points for ABR loans when not in an Investment Grade Period (as defined in the amended and restated credit agreement) and from 112.5 to 175 basis points for LIBOR loans and from 12.5 to 75 basis points for ABR loans during an Investment Grade Period. The revolving credit facility also provides for a commitment fee on the unused available balance and is calculated at annual rates ranging from 30 to 42.5 basis points when not in an Investment Grade Period and from 12.5 to 27.5 basis points during an Investment Grade Period. The Company is currently not in an Investment Grade Period. From time to time, the Company uses the LIBOR benchmark rate for borrowings under its revolving credit facility. In July 2017, the U.K. Financial Conduct Authority (FCA) announced that it will no longer compel banks to submit rates that are currently used to calculate LIBOR after 2021. In November 2020, the FCA and ICE Benchmark Administration, which administers LIBOR quotations, announced the intention to consult on the extension of most LIBOR tenors to June 30, 2023 for legacy contracts only. The Company’s revolving credit facility has a term that extends beyond June 30, 2023. The Company’s revolving credit facility also provides that in the event that the LIBOR benchmark rate is no longer available, the Company and its lenders will endeavor to establish an alternative interest rate based on the then prevailing market convention for purposes of LIBOR borrowings. The Company currently has no borrowings outstanding under its revolving credit facility and does not expect the transition to an alternative rate to have a material impact on its results of operations or cash flows. The revolving credit facility contains various customary covenants, which include the following (with all calculations based on definitions contained in the amended and restated credit agreement): (a) Maintenance of a minimum asset coverage ratio of 1.75 to 1.0. (b) Maintenance of a minimum annual coverage ratio of consolidated cash flow to interest expense for the trailing four quarters of 2.8 to 1.0; and (c) Maintenance of a minimum current ratio of 1.0 to 1.0. At December 31, 2020, there were no borrowings outstanding under the Company's revolving credit facility and unused commitments were $1.5 billion. The Company's weighted-average effective interest rate for the revolving credit facility during the year ended December 31, 2020 and 2019 was approximately 4.0 percent and 6.3 percent, respectively. During 2019, the Company incurred $7.4 million of debt issuance costs in connection with the amended and restated credit agreement, which were capitalized and will be amortized over the term of the amended and restated agreement. The remaining unamortized costs of $3.4 million will also be amortized over the term of the amended and restated agreement in accordance with ASC 470-50, Debt Modifications and Extinguishments.

Derivative Instruments

Derivative Instruments	12 Months Ended
Derivative Instruments	Dec. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative Instruments As of December 31, 2020, the Company had the following outstanding financial commodity derivatives: Collars Floor Ceiling Swaps Type of Contract Volume (Mmbtu) Contract Period Range Weighted-Average Range Weighted- Average Weighted- Average Natural gas (NYMEX) 18,250,000 Jan. 2021-Dec. 2021 $ 2.74 Natural gas (NYMEX) 164,250,000 Jan. 2021-Dec. 2021 $2.50 - $2.85 $ 2.68 $2.83 - $3.94 $ 3.09 Natural gas (NYMEX) 10,700,000 Apr. 2021-Oct. 2021 $ — $ 2.50 $ — $ 2.80 Natural gas (NYMEX) 10,700,000 Apr. 2021-Oct. 2021 $ 2.75 In early 2021, the Company entered into the following financial commodity derivatives: Swaps Type of Contract Volume (Mmbtu) Contract Period Weighted- Average ($/Mmbtu) Natural gas (NYMEX) 10,700,000 Apr. 2021-Oct. 2021 $ 2.81 Effect of Derivative Instruments on the Consolidated Balance Sheet Fair Values of Derivative Instruments Derivative Assets Derivative Liabilities December 31, December 31, (In thousands) Balance Sheet Location 2020 2019 2020 2019 Commodity contracts Derivative instruments (current) $ 26,209 $ 31 $ — $ — Commodity contracts Accrued liabilities — — — 9 Offsetting of Derivative Assets and Liabilities in the Consolidated Balance Sheet December 31, (In thousands) 2020 2019 Derivative assets Gross amounts of recognized assets $ 26,354 $ 47 Gross amounts offset in the consolidated balance sheet (145) (16) Net amounts of assets presented in the consolidated balance sheet 26,209 31 Gross amounts of financial instruments not offset in the consolidated balance sheet — — Net amount $ 26,209 $ 31 Derivative liabilities Gross amounts of recognized liabilities $ 145 $ 25 Gross amounts offset in the consolidated balance sheet (145) (16) Net amounts of liabilities presented in the consolidated balance sheet — 9 Gross amounts of financial instruments not offset in the consolidated balance sheet — — Net amount $ — $ 9 Effect of Derivative Instruments on the Consolidated Statement of Operations Year Ended December 31, (In thousands) 2020 2019 2018 Cash received (paid) on settlement of derivative instruments Gain (loss) on derivative instruments $ 35,218 $ 138,450 $ (41,631) Non-cash gain (loss) on derivative instruments Gain (loss) on derivative instruments 26,186 (57,642) 86,063 $ 61,404 $ 80,808 $ 44,432 Additional Disclosures about Derivative Instruments The use of derivative instruments involves the risk that the counterparties will be unable to meet their obligations under the agreements. The Company's counterparties are primarily commercial banks and financial service institutions that management believes present minimal credit risk and its derivative contracts are with multiple counterparties to minimize its exposure to any individual counterparty. The Company performs both quantitative and qualitative assessments of these counterparties based on their credit ratings and credit default swap rates where applicable. Certain counterparties to the Company's derivative instruments are also lenders under its revolving credit facility. The Company's revolving credit facility and derivative instruments contain certain cross default and acceleration provisions that may require immediate payment of its derivative liabilities in certain situations. The Company also has netting arrangements with each of its counterparties that allow it to offset assets and liabilities from separate derivative contracts with that counterparty.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
Fair Value Measurements	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Financial Assets and Liabilities The following fair value hierarchy table presents information about the Company's financial assets and liabilities measured at fair value on a recurring basis: (In thousands) Quoted Prices in Significant Other Significant Balance at Assets Deferred compensation plan $ 22,510 $ — $ — $ 22,510 Derivative instruments — 2,647 23,707 26,354 Total assets $ 22,510 $ 2,647 $ 23,707 $ 48,864 Liabilities Deferred compensation plan $ 30,581 $ — $ — $ 30,581 Derivative instruments — — 145 145 Total liabilities $ 30,581 $ — $ 145 $ 30,726 (In thousands) Quoted Prices in Significant Other Significant Balance at Assets Deferred compensation plan $ 18,381 $ — $ — $ 18,381 Derivative instruments — 44 3 47 Total assets $ 18,381 $ 44 $ 3 $ 18,428 Liabilities Deferred compensation plan $ 27,012 $ — $ — $ 27,012 Derivative instruments — — 25 25 Total liabilities $ 27,012 $ — $ 25 $ 27,037 The Company's investments associated with its deferred compensation plan consist of mutual funds and deferred shares of the Company's common stock that are publicly traded and for which market prices are readily available. The derivative instruments were measured based on quotes from the Company's counterparties or internal models. Such quotes and models have been derived using an income approach that considers various inputs including current market and contractual prices for the underlying instruments, quoted forward commodity prices, basis differentials, volatility factors and interest rates for a similar length of time as the derivative contract term as applicable. Estimates are derived from or verified using relevant NYMEX futures contracts and/or are compared to multiple quotes obtained from counterparties for reasonableness. The determination of the fair values presented above also incorporates a credit adjustment for non-performance risk. The Company measured the non-performance risk of its counterparties by reviewing credit default swap spreads for the various financial institutions with which it has derivative contracts while non-performance risk of the Company is evaluated using a market credit spread provided by several of the Company's banks. The Company has not incurred any losses related to non-performance risk of its counterparties and does not anticipate any material impact on its financial results due to non-performance by third parties. The most significant unobservable inputs relative to the Company's Level 3 derivative contracts are volatility factors. An increase (decrease) in these unobservable inputs would result in an increase (decrease) in fair value, respectively. The Company does not have access to the specific assumptions used in its counterparties' valuation models. Consequently, additional disclosures regarding significant Level 3 unobservable inputs were not provided. The following table sets forth a reconciliation of changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy: Year Ended December 31, (In thousands) 2020 2019 2018 Balance at beginning of period $ (22) $ 21,976 $ (28,398) Total gain (loss) included in earnings 40,563 24,794 31,184 Settlement (gain) loss (16,979) (46,792) 19,190 Transfers in and/or out of Level 3 — — — Balance at end of period $ 23,562 $ (22) $ 21,976 Change in unrealized gains (losses) relating to assets and liabilities still held at the end of the period $ 23,562 $ (22) $ 19,732 Non-Financial Assets and Liabilities The Company discloses or recognizes its non-financial assets and liabilities, such as impairments of oil and gas properties or acquisitions, at fair value on a nonrecurring basis. As none of the Company's other non-financial assets and liabilities were measured at fair value as of December 31, 2020, 2019 and 2018, additional disclosures were not required. The estimated fair value of the Company's asset retirement obligations at inception is determined by utilizing the income approach by applying a credit-adjusted risk-free rate, which takes into account the Company's credit risk, the time value of money, and the current economic state to the undiscounted expected abandonment cash flows. Given the unobservable nature of the inputs, the measurement of the asset retirement obligations was classified as Level 3 in the fair value hierarchy. Fair Value of Other Financial Instruments The estimated fair value of other financial instruments is the amount at which the instrument could be exchanged currently between willing parties. The carrying amounts reported in the Consolidated Balance Sheet for cash and cash equivalents and restricted cash approximate fair value due to the short-term maturities of these instruments. Cash and cash equivalents and restricted cash are classified as Level 1 in the fair value hierarchy and the remaining financial instruments are classified as Level 2. The Company uses available market data and valuation methodologies to estimate the fair value of debt. The fair value of debt is the estimated amount the Company would have to pay a third party to assume the debt, including a credit spread for the difference between the issue rate and the period end market rate. The credit spread is the Company's default or repayment risk. The credit spread (premium or discount) is determined by comparing the Company's senior notes and revolving credit facility to new issuances (secured and unsecured) and secondary trades of similar size and credit statistics for both public and private debt. The fair value of all senior notes and the revolving credit facility is based on interest rates currently available to the Company. The Company's debt is valued using an income approach and classified as Level 3 in the fair value hierarchy. The carrying amount and fair value of debt is as follows: December 31, 2020 December 31, 2019 (In thousands) Carrying Estimated Carrying Estimated Long-term debt $ 1,133,924 $ 1,213,811 $ 1,220,025 $ 1,260,259 Current maturities (188,000) (189,332) (87,000) (88,704) Long-term debt, excluding current maturities $ 945,924 $ 1,024,479 $ 1,133,025 $ 1,171,555

Asset Retirement Obligations

Asset Retirement Obligations	12 Months Ended
Asset Retirement Obligations	Dec. 31, 2020
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligations	Asset Retirement Obligations Activity related to the Company's asset retirement obligations is as follows: Year Ended December 31, (In thousands) 2020 2019 Balance at beginning of period $ 72,098 $ 51,622 Liabilities incurred 10,008 7,646 Liabilities settled (322) (1,467) Accretion expense 4,205 3,430 Change in estimate — 10,867 Balance at end of period 85,989 72,098 Less: current asset retirement obligation (500) (500) Noncurrent asset retirement obligation $ 85,489 $ 71,598

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Transportation and Gathering Agreements The Company has entered into certain transportation and gathering agreements with various pipeline carriers. Under certain of these agreements, the Company is obligated to ship minimum daily quantities, or pay for any deficiencies at a specified rate. The Company's forecasted production to be shipped on these pipelines is expected to exceed minimum daily quantities provided in the agreements. The Company is also obligated under certain of these arrangements to pay a demand charge for firm capacity rights on pipeline systems regardless of the amount of pipeline capacity utilized by the Company. If the Company does not utilize the capacity, it can release it to others, thus reducing its potential liability. As of December 31, 2020, the Company's future minimum obligations under transportation and gathering agreements are as follows: (In thousands) 2021 $ 105,304 2022 191,455 2023 185,913 2024 179,772 2025 169,050 Thereafter 1,184,624 $ 2,016,118 Lease Commitments The Company has operating leases for office space, surface use agreements, compressor services and other leases. The leases have remaining terms ranging from six months to 25 years, including options to extend leases that the Company is reasonably certain to exercise. During the year ended December 31, 2020, the Company recognized operating lease cost and variable lease cost of $5.4 million and $1.1 million, respectively. During the year ended December 31, 2019, the Company recognized operating lease cost and variable lease cost of $11.5 million and $6.6 million, respectively. Short-term leases. The Company leases drilling rigs, fracturing and other equipment under lease terms ranging from 30 days to one year. Lease cost of $26.3 million and $267.9 million was recognized on short-term leases during the year ended December 31, 2020 and 2019, respectively. Certain lease costs are capitalized and included in Properties and equipment, net in the Consolidated Balance Sheet because they relate to drilling and completion activities, while other costs are expensed because they relate to production and administrative activities. As of December 31, 2020, the Company’s future undiscounted minimum cash payment obligations for its operating lease liabilities are as follows: (In thousands) Year Ending December 31, 2021 $ 5,556 2022 4,894 2023 4,613 2024 4,653 2025 4,675 Thereafter 20,495 Total undiscounted future lease payments 44,886 Present value adjustment (11,267) Net operating lease liabilities $ 33,619 Supplemental cash flow information related to leases was as follows: Year Ended December 31, (In thousands) 2020 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 5,338 $ 4,614 Investing cash flows from operating leases $ — $ 6,647 Information regarding the weighted-average remaining lease term and the weighted-average discount rate for operating leases is summarized below: December 31, 2020 2019 Weighted-average remaining lease term (in years) Operating leases 11.1 12.1 Weighted-average discount rate Operating leases 5.0 % 5.0 % Legal Matters Pennsylvania Office of Attorney General Matter In June 2020, the Office of Attorney General of the Commonwealth of Pennsylvania informed the Company that it will pursue certain misdemeanor and felony charges against the Company related to alleged violations of the Pennsylvania Clean Streams Law, which prohibits discharge of industrial wastes. The Company is vigorously defending itself against such charges; however, the proceedings could result in fines or penalties against the Company. At this time, it is not possible to estimate the amount of any fines or penalties, or the range of such fines or penalties, that are reasonably possible in this case. Other The Company is a defendant in various other legal proceedings arising in the normal course of business. All known liabilities are accrued when management determines they are probable based on its best estimate of the potential loss. While the outcome and impact of these legal proceedings on the Company cannot be predicted with certainty, management believes that the resolution of these proceedings will not have a material effect on the Company's financial position, results of operations or cash flows. Contingency Reserves When deemed necessary, the Company establishes reserves for certain legal proceedings. The establishment of a reserve is based on an estimation process that includes the advice of legal counsel and subjective judgment of management. While management believes these reserves to be adequate, it is reasonably possible that the Company could incur additional losses with respect to those matters for which reserves have been established. The Company believes that any such amount above the

Revenue Recognition

Revenue Recognition	12 Months Ended
Revenue Recognition	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Revenue Recognition	Revenue Recognition Disaggregation of Revenue The following table presents revenues from contracts with customers disaggregated by product: Year Ended December 31, (In thousands) 2020 2019 2018 OPERATING REVENUES Natural gas $ 1,404,989 $ 1,985,240 $ 1,881,150 Crude oil and condensate — — 48,722 Brokered natural gas — — 209,530 Other 231 229 4,314 Total revenues from contracts with customers $ 1,405,220 $ 1,985,469 $ 2,143,716 All of the Company’s revenues from contracts with customers represent products transferred at a point in time as control is transferred to the customer and generated in the United States. Transaction Price Allocated to Remaining Performance Obligations A significant number of the Company’s product sales contracts are short-term in nature with a contract term of one year or less. For those contracts, the Company has utilized the practical expedient exempting the Company from disclosure of the transaction price allocated to remaining performance obligations if the performance obligation is part of a contract that has an original expected duration of one year or less. As of December 31, 2020, the Company has $8.9 billion of unsatisfied performance obligations related to natural gas sales that have a fixed pricing component and a contract term greater than one year. The Company expects to recognize these obligations over periods ranging from three Contract Balances

Income Taxes

Income Taxes	12 Months Ended
Income Taxes	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Income tax expense is summarized as follows: Year Ended December 31, (In thousands) 2020 2019 2018 Current Federal $ (31,838) $ (29,584) $ (95,191) State 655 4,320 6,682 (31,183) (25,264) (88,509) Deferred Federal 67,451 233,136 230,643 State 4,326 11,282 (1,040) 71,777 244,418 229,603 Income tax expense $ 40,594 $ 219,154 $ 141,094 Income tax expense was different than the amounts computed by applying the statutory federal income tax rate as follows: Year Ended December 31, 2020 2019 2018 (In thousands, except rates) Amount Rate Amount Rate Amount Rate Computed "expected" federal income tax $ 50,636 21.00 % $ 189,047 21.00 % $ 146,609 21.00 % State income tax, net of federal income tax benefit 4,486 1.86 % 14,773 1.64 % 11,850 1.70 % Deferred tax adjustment related to change in overall state tax rate 1,213 0.50 % (660) (0.07) % (15,208) (2.18) % Valuation allowance (3,800) (1.58) % 17,676 1.96 % 8,975 1.29 % Excess executive compensation 5,249 2.18 % 1,935 0.21 % 1,382 0.20 % Reserve on uncertain tax positions 5,964 2.47 % 5 — % — — % Tax credits generated (23,216) (9.63) % — — % — — % Tax Act — — % — — % (11,367) (1.63) % Other, net 62 0.04 % (3,622) (0.40) % (1,147) (0.16) % Income tax expense $ 40,594 16.84 % $ 219,154 24.34 % $ 141,094 20.21 % In 2020, the Company's overall effective tax rate decreased compared to 2019, primarily due to research and development tax credit benefits recorded in 2020 related to amended prior year returns. The overall effective tax rate increased in 2019 compared to 2018 primarily due to larger tax benefits recorded in 2018 related to the Tax Cuts and Jobs Act (the Tax Act) and changes in the overall state tax rate. The composition of net deferred tax liabilities is as follows: December 31, (In thousands) 2020 2019 Deferred Tax Assets Net operating losses $ 22,177 $ 22,360 Alternative minimum tax credits — 22,120 Incentive compensation 16,427 17,776 Deferred compensation 5,753 5,463 Post-retirement benefits 7,482 7,847 Equity method investments — 21,454 Capital loss carryforward 16,486 — Leases 7,709 8,192 Other 3,267 1,336 Less: valuation allowance (28,231) (31,763) Total 51,070 74,785 Deferred Tax Liabilities Properties and equipment 809,919 768,692 Equity method investments 1,649 — Leases 7,709 8,192 Derivative instruments 5,988 5 Total 825,265 776,889 Net deferred tax liabilities $ 774,195 $ 702,104 As of December 31, 2020, the Company had gross state net operating loss carryforwards of $382.5 million, the majority of which expire between 2025 and 2040. Under the Coronavirus Aid, Relief, and Economic Security (CARES) Act, enacted in 2020, the Company fully utilized its remaining alternative minimum tax credits on its 2019 tax return. The Company also incurred a capital loss on the sale of equity method investments in 2020, and recorded a gross capital loss carryforward of $72.2 million, which can only be used to offset future capital gains, and will expire in 2025. As of December 31, 2020, the Company had $13.1 million of valuation allowances on the deferred tax benefits related to state NOLs, and $14.9 million of valuation allowances on the deferred tax benefit related to the capital loss carryforward. The Company believes it is more likely than not that the remainder of its deferred tax benefits will be utilized prior to their expiration. Unrecognized Tax Benefits A reconciliation of unrecognized tax benefits is as follows: Year Ended December 31, (In thousands) 2020 2019 2018 Balance at beginning of year $ 520 $ 16,850 $ 663 Additions for tax positions of current year 499 — — Additions for tax positions of prior years 5,465 — 16,187 Reductions for tax positions of prior years — (16,330) — Balance at end of year $ 6,484 $ 520 $ 16,850 During 2020, the Company recorded a $6.0 million reserve for unrecognized tax benefits related to research and development tax credits on prior year amended returns and current year estimates, and a $0.5 million liability for accrued interest associated with the uncertain tax position. As of December 31, 2020, the Company's overall net reserve for unrecognized tax positions was $6.5 million, with a $0.6 million liability for accrued interest on the uncertain tax positions. If recognized, the net tax benefit of $6.5 million would not have a material effect on the Company's effective tax rate.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
Employee Benefit Plans	Dec. 31, 2020
Retirement Benefits [Abstract]
Employee Benefit Plans	Employee Benefit Plans Postretirement Benefits The Company provides certain health care benefits for retired employees, including their spouses, eligible dependents and surviving spouses (retirees). These benefits are commonly called postretirement benefits. The health care plans are contributory, with participants' contributions adjusted annually. Most employees become eligible for these benefits if they meet certain age and service requirements at retirement. The Company provided postretirement benefits to 337 retirees and their dependents at the end of 2020 and 310 retirees and their dependents at the end of 2019. Obligations and Funded Status The funded status represents the difference between the accumulated benefit obligation of the Company's postretirement plan and the fair value of plan assets at December 31. The postretirement plan does not have any plan assets; therefore, the unfunded status is equal to the amount of the December 31 accumulated benefit obligation. The change in the Company's postretirement benefit obligation is as follows: Year Ended December 31, (In thousands) 2020 2019 2018 Change in Benefit Obligation Benefit obligation at beginning of year $ 34,438 $ 29,777 $ 31,050 Service cost 1,493 1,533 1,776 Interest cost 974 1,283 1,172 Actuarial (gain) loss (2,119) 3,279 (3,165) Benefits paid (2,042) (1,434) (1,056) Benefit obligation at end of year $ 32,744 $ 34,438 $ 29,777 Change in Plan Assets Fair value of plan assets at end of year — — — Funded status at end of year $ (32,744) $ (34,438) $ (29,777) Amounts Recognized in the Balance Sheet Amounts recognized in the balance sheet consist of the following: December 31, (In thousands) 2020 2019 2018 Current liabilities $ 2,031 $ 1,725 $ 1,865 Non-current liabilities 30,713 32,713 27,912 $ 32,744 $ 34,438 $ 29,777 Amounts Recognized in Accumulated Other Comprehensive Income (Loss) Amounts recognized in accumulated other comprehensive income (loss) consist of the following: December 31, (In thousands) 2020 2019 2018 Net actuarial (gain) loss $ (57) $ 2,025 $ (1,253) Prior service cost (3,078) (3,787) (4,497) $ (3,135) $ (1,762) $ (5,750) Components of Net Periodic Benefit Cost and Other Amounts Recognized in Other Comprehensive Income (Loss) Year Ended December 31, (In thousands) 2020 2019 2018 Components of Net Periodic Postretirement Benefit Cost Service cost $ 1,493 $ 1,533 $ 1,776 Interest cost 974 1,283 1,172 Amortization of prior service cost (709) (709) (709) Amortization of net loss (36) — — Net periodic postretirement cost $ 1,722 $ 2,107 $ 2,239 Other Changes in Benefit Obligations Recognized in Other Comprehensive Income (Loss) Net (gain) loss $ (2,118) $ 3,279 $ (3,165) Amortization of prior service cost 709 709 709 Amortization of net loss 36 — — Total recognized in other comprehensive income (1,373) 3,988 (2,456) Total recognized in net periodic benefit cost (income) and other comprehensive income $ 349 $ 6,095 $ (217) Assumptions Assumptions used to determine projected postretirement benefit obligations and postretirement costs are as follows: December 31, 2020 2019 2018 Discount rate (1) 2.65 % 3.50 % 4.45 % Health care cost trend rate for medical benefits assumed for next year (pre-65) 6.75 % 7.00 % 7.25 % Health care cost trend rate for medical benefits assumed for next year (post-65) 5.00 % 5.25 % 5.50 % Ultimate trend rate (pre-65) 4.50 % 4.50 % 4.50 % Ultimate trend rate (post-65) 4.50 % 4.50 % 4.50 % Year that the rate reaches the ultimate trend rate (pre-65) 2030 2030 2030 Year that the rate reaches the ultimate trend rate (post-65) 2023 2023 2023 _______________________________________________________________________________ (1) Represents the year end rates used to determine the projected benefit obligation. To compute postretirement cost in 2020, 2019 and 2018, respectively, the beginning of year discount rates of 3.50 percent, 4.45 percent and 3.85 percent were used. Coverage provided to participants age 65 and older is under a fully-insured arrangement. The Company subsidy is limited to 60 percent of the expected annual fully-insured premium for participants age 65 and older. For all participants under age 65, the Company subsidy for all retiree medical and prescription drug benefits, beginning January 1, 2006, was limited to an aggregate annual amount not to exceed $648,000. This limit increases by 3.5 percent annually thereafter. Cash Flows Contributions. The Company expects to contribute approximately $2.1 million to the postretirement benefit plan in 2021. Estimated Future Benefit Payments. The following estimated benefit payments under the Company's postretirement plans, which reflect expected future service, are expected to be paid as follows: (In thousands) 2021 $ 2,058 2022 2,085 2023 1,984 2024 1,860 2025 1,789 Years 2026 - 2030 9,018 Savings Investment Plan The Company has a Savings Investment Plan (SIP), which is a defined contribution plan. The Company matches a portion of employees' contributions in cash. Participation in the SIP is voluntary and all regular employees of the Company are eligible to participate. The Company matches employee contributions dollar-for-dollar, up to the maximum IRS limit, on the first six percent of an employee's pretax earnings. The SIP also provides for discretionary profit sharing contributions in an amount equal to 10 percent of an eligible plan participant's salary and bonus. During the years ended December 31, 2020, 2019 and 2018, the Company made contributions of $5.6 million, $5.8 million and $5.9 million, respectively, which are included in general and administrative expense in the Consolidated Statement of Operations. The Company's common stock is an investment option within the SIP. Deferred Compensation Plan The Company has a deferred compensation plan which is available to officers and certain members of the Company's management group and acts as a supplement to the SIP. The Internal Revenue Code does not cap the amount of compensation that may be taken into account for purposes of determining contributions to the deferred compensation plan and does not impose limitations on the amount of contributions to the deferred compensation plan. At the present time, the Company anticipates making a contribution to the deferred compensation plan on behalf of a participant in the event that Internal Revenue Code limitations cause a participant to receive less than the Company matching contribution under the SIP. The assets of the deferred compensation plan are held in a rabbi trust and are subject to additional risk of loss in the event of bankruptcy or insolvency of the Company. Under the deferred compensation plan, the participants direct the deemed investment of amounts credited to their accounts. The trust assets are invested in either mutual funds that cover the investment spectrum from equity to money market, or may include holdings of the Company's common stock, which is funded by the issuance of shares to the trust. The mutual funds are publicly traded and have market prices that are readily available. The Company's common stock is not currently an investment option in the deferred compensation plan. Shares of the Company's stock currently held in the deferred compensation plan represent vested performance share awards that were previously deferred into the rabbi trust. Settlement payments are made to participants in cash, either in a lump sum or in periodic installments. The market value of the trust assets, excluding the Company's common stock, was $22.5 million and $18.4 million at December 31, 2020 and 2019, respectively, and is included in other assets in the Consolidated Balance Sheet. Related liabilities, including the Company's common stock, totaled $30.6 million and $27.0 million at December 31, 2020 and 2019, respectively, and are included in other liabilities in the Consolidated Balance Sheet. With the exception of the Company's common stock, there is no impact on earnings or earnings per share from the changes in market value of the deferred compensation plan assets because the changes in market value of the trust assets are offset completely by changes in the value of the liability, which represents trust assets belonging to plan participants. As of December 31, 2020 and 2019, 495,774 shares and 495,774 shares of the Company's common stock were held in the rabbi trust, respectively. These shares were recorded at the market value on the date of deferral, which totaled $5.1 million and $5.1 million at December 31, 2020 and 2019, respectively, and is included in additional paid-in capital in stockholders' equity in the Consolidated Balance Sheet. The Company recognized compensation (benefit) expense of ($0.6 million), ($2.4 million) and ($3.1 million) in 2020, 2019 and 2018, respectively, which is included in general and administrative expense in the Consolidated Statement of Operations representing the increase (decrease) in the closing price of the Company's shares held in the trust. The Company's common stock issued to the trust is not considered outstanding for purposes of calculating basic earnings per share, but is considered a common stock equivalent in the calculation of diluted earnings per share. The Company made contributions to the deferred compensation plan of $1.0 million, $1.0 million and $1.1 million in 2020, 2019 and 2018, respectively, which are included in general and administrative expense in the Consolidated Statement of Operations.

Capital Stock

Capital Stock	12 Months Ended
Capital Stock	Dec. 31, 2020
Equity [Abstract]
Capital Stock	Capital Stock Incentive Plans On May 1, 2014, the Company’s shareholders approved the 2014 Incentive Plan. Under the 2014 Incentive Plan, incentive and non-statutory stock options, stock appreciation rights (SARs), stock awards, cash awards and performance share awards may be granted to key employees, consultants and officers of the Company. Non-employee directors of the Company may be granted discretionary awards under the 2014 Incentive Plan consisting of stock options or stock awards. A total of 18.0 million shares of common stock may be issued under the 2014 Incentive Plan. Under the 2014 Incentive Plan, no more than 10.0 million shares may be issued pursuant to incentive stock options. No additional awards may be granted under the 2014 Incentive Plan on or after May 1, 2024. At December 31, 2020, approximately 11.1 million shares are available for issuance under the 2014 Incentive Plan. No additional awards will be granted under any of the Company’s prior plans, including the 2004 Incentive Plan. Awards outstanding under the 2004 Incentive Plan will remain outstanding in accordance with their original terms and conditions. Treasury Stock In August 1998, the Board of Directors authorized a share repurchase program under which the Company may purchase shares of common stock in the open market or in negotiated transactions. The timing and amount of these stock purchases are determined at the discretion of management. The Company may use the repurchased shares to fund stock compensation programs presently in existence, or for other corporate purposes. All purchases executed to date have been through open market transactions. There is no expiration date associated with the authorization to repurchase shares of the Company. During 2020, there were no share repurchases. During the years ended December 31, 2019 and 2018, the Company repurchased 25.5 million shares for a total cost of $488.5 million and 38.5 million shares for a total cost of $904.1 million, respectively. Since the authorization date and subsequent authorizations, the Company has repurchased 99.0 million shares, of which 20.0 million shares have been retired, for a total cost of approximately $1.9 billion. No treasury shares have been delivered or sold by the Company subsequent to the repurchase. As of December 31, 2020, 79.0 million shares were held as treasury stock and 11.0 million shares were available for repurchase under the share repurchase plan. Dividend Restrictions The Board of Directors of the Company determines the amount of future cash dividends, if any, to be declared and paid on the common stock depending on, among other things, the Company's financial condition, funds from operations, the level of its capital and exploration expenditures, and its future business prospects. None of the senior note or credit agreements in place have restricted payment provisions or other provisions limiting dividends

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
Stock-Based Compensation	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-Based Compensation General Stock-based compensation expense for the years ended December 31, 2020, 2019 and 2018 was $43.2 million, $30.8 million and $33.1 million, respectively, and is included in general and administrative expense in the Consolidated Statement of Operations. The related income tax benefit for the years ended December 31, 2020, 2019 and 2018 was $10.0 million, $7.0 million and $7.6 million, respectively. Restricted Stock Awards Restricted stock awards are granted from time to time to employees of the Company. The fair value of restricted stock grants is based on the closing stock price on the grant date. Restricted stock awards generally vest either at the end of a three year service period or on a graded or graduated vesting basis at each anniversary date over a three For awards that vest at the end of the service period, expense is recognized ratably using a straight-line approach over the service period. Under the graded or graduated approach, the Company recognizes compensation cost ratably over the requisite service period, as applicable, for each separately vesting tranche as though the awards are, in substance, multiple awards. For most restricted stock awards, vesting is dependent upon the employees' continued service with the Company, with the exception of employment termination due to death, disability or retirement. If included in the grant award, the Company accelerates the vesting period for retirement-eligible employees for purposes of recognizing compensation expense in accordance with the vesting provisions of the Company's stock-based compensation programs. The Company used an annual forfeiture rate assumption of five percent for purposes of recognizing stock-based compensation expense for restricted stock awards. The annual forfeiture rates were based on the Company's actual forfeiture history for this type of award to various employee groups. The following table is a summary of restricted stock award activity: Year Ended December 31, 2020 2019 2018 Shares Weighted- Shares Weighted- Shares Weighted- Outstanding at beginning of period 58,834 $ 25.19 150,293 $ 28.12 161,450 $ 28.00 Granted — — 55,500 25.29 — — Vested (6,334) 24.39 (143,959) 28.29 (7,157) 25.17 Forfeited (2,000) 25.29 (3,000) 25.29 (4,000) 28.45 Outstanding at end of period (1)(2) 50,500 $ 25.29 58,834 $ 25.19 150,293 $ 28.12 __________________________________________________________________ (1) As of December 31, 2020, the aggregate intrinsic value was $0.8 million and was calculated by multiplying the closing market price of the Company's stock on December 31, 2020 by the number of non-vested restricted stock awards outstanding. (2) As of December 31, 2020, the weighted average remaining contractual term of non-vested restricted stock awards outstanding was 1.4 years. Compensation expense recorded for all restricted stock awards for the years ended December 31, 2020, 2019 and 2018 was $0.4 million, $1.3 million and $2.8 million, respectively. Unamortized expense as of December 31, 2020 for all outstanding restricted stock awards was $0.7 million and will be recognized over the next 1.4 years. The total fair value of restricted stock awards that vested during 2020, 2019 and 2018 was $0.2 million, $4.1 million and $0.2 million, respectively. Restricted Stock Units Restricted stock units are granted from time to time to non-employee directors of the Company. The fair value of the restricted stock units is based on the closing stock price on the grant date. These units vest immediately and compensation expense is recorded immediately. Restricted stock units are issued when the director ceases to be a director of the Company. The following table is a summary of restricted stock unit activity: Year Ended December 31, 2020 2019 2018 Shares Weighted- Shares Weighted- Shares Weighted- Outstanding at beginning of period 574,219 $ 18.47 490,415 $ 17.41 407,563 $ 16.17 Granted and fully vested 130,065 15.88 83,804 24.70 82,852 23.47 Issued — — — — — — Forfeited — — — — — — Outstanding at end of period (1)(2) 704,284 $ 17.99 574,219 $ 18.47 490,415 $ 17.41 _______________________________________________________________________________ (1) As of December 31, 2020, the aggregate intrinsic value was $11.5 million and was calculated by multiplying the closing market price of the Company's stock on December 31, 2020 by the number of outstanding restricted stock units. (2) Due to the immediate vesting of the units and the unknown term of each director, the weighted-average remaining contractual term in years has not been provided. Compensation expense recorded for all restricted stock units for the year ended December 31, 2020, 2019 and 2018 was $2.1 million, $2.1 million and $1.9 million, respectively, which reflects the total fair value of these units. Performance Share Awards The Company grants three types of performance share awards: two based on performance conditions measured against the Company's internal performance metrics (Employee Performance Share Awards and Hybrid Performance Share Awards) and one based on market conditions measured based on the Company's performance relative to a predetermined peer group (TSR Performance Share Awards). The performance period for these awards commences on January 1 of the respective year in which the award was granted and extends over a three-year performance period. For all performance share awards, the Company used an annual forfeiture rate assumption ranging from zero percent to seven percent for purposes of recognizing stock-based compensation expense for its performance share awards. Performance Share Awards Based on Internal Performance Metrics The fair value of performance share award grants based on internal performance metrics is based on the closing stock price on the grant date. Each performance share award represents the right to receive up to 100 percent of the award in shares of common stock. Employee Performance Share Awards. The Employee Performance Share Awards vest at the end of the three-year performance period and the performance metrics are set by the Company's Compensation Committee. For the awards granted in 2020, an employee will earn 100 percent of the award on the third anniversary, provided that the Company averages $100 million or more of operating cash flow during the three-year performance period. For awards granted in 2019 and 2018, an employee will earn one-third of the award for each of the three performance metrics. The three performance metrics are based on the Company's average production, average finding costs and average reserve replacement over a three-year performance period. Based on the Company's probability assessment at December 31, 2020, it is considered probable that all of the criteria for these awards will be met. The following table is a summary of activity for Employee Performance Share Awards: Year Ended December 31, 2020 2019 2018 Shares Weighted- Shares Weighted- Shares Weighted- Outstanding at beginning of period 1,259,287 $ 23.64 1,280,021 $ 22.22 1,095,970 $ 23.31 Granted 722,500 15.60 526,730 24.95 531,670 23.25 Issued and fully vested (334,640) 22.60 (388,370) 20.49 (315,970) 27.71 Forfeited (37,023) 20.38 (159,094) 24.29 (31,649) 22.33 Outstanding at end of period 1,610,124 $ 20.31 1,259,287 $ 23.64 1,280,021 $ 22.22 Hybrid Performance Share Awards. The Hybrid Performance Share Awards have a three-year graded performance period. The awards vest 25 percent on each of the first and second anniversary dates and 50 percent on the third anniversary provided that the Company has $100 million or more of operating cash flow for the year preceding the vesting date, as set by the Company's Compensation Committee. If the Company does not meet the performance metric for the applicable period, then the portion of the performance shares that would have been issued on that anniversary date will be forfeited. Based on the Company's probability assessment at December 31, 2020, it is considered probable that the criteria for these awards will be met. The following table is a summary of activity for the Hybrid Performance Share Awards: Year Ended December 31, 2020 2019 2018 Shares Weighted- Shares Weighted- Shares Weighted- Outstanding at beginning of period 692,788 $ 23.90 662,388 $ 22.48 574,354 $ 22.72 Granted 506,412 15.60 315,029 24.95 321,720 23.25 Issued and fully vested (295,649) 23.40 (284,629) 21.78 (233,686) 24.12 Forfeited — — — — — — Outstanding at end of period 903,551 $ 19.41 692,788 $ 23.90 662,388 $ 22.48 Performance Share Awards Based on Market Conditions These awards have both an equity and liability component, with the right to receive up to the first 100 percent of the award in shares of common stock and the right to receive up to an additional 100 percent of the value of the award in excess of the equity component in cash. The equity portion of these awards is valued on the grant date and is not marked to market, while the liability portion of the awards is valued as of the end of each reporting period on a mark-to-market basis. The Company calculates the fair value of the equity and liability portions of the awards using a Monte Carlo simulation model. TSR Performance Share Awards. The TSR Performance Share Awards granted are earned, or not earned, based on the comparative performance of the Company's common stock measured against a predetermined group of companies in the Company's peer group over a three-year performance period. The following table is a summary of activity for the TSR Performance Share Awards: Year Ended December 31, 2020 2019 2018 Shares Weighted- Average Grant Date Fair Value per Share (1) Shares Weighted- Average Grant Date Fair Value per Share (1) Shares Weighted- Average Grant Date Fair Value per Share (1) Outstanding at beginning of period 1,428,634 $ 20.17 1,299,868 $ 19.47 1,109,708 $ 19.23 Granted 862,180 13.79 536,673 20.63 482,581 19.92 Issued and fully vested (891,961) 19.89 (407,907) 18.57 (292,421) 19.29 Forfeited — — — — — — Outstanding at end of period 1,398,853 $ 16.41 1,428,634 $ 20.17 1,299,868 $ 19.47 _______________________________________________________________________________ (1) The grant date fair value figures in this table represent the fair value of the equity component of the performance share awards. The current portion of the liability, included in accrued liabilities in the Consolidated Balance Sheet at December 31, 2019 was $6.1 million. There was no current liability recorded at December 31, 2020. The non-current portion of the liability for the TSR Performance Share Awards, included in other liabilities in the Consolidated Balance Sheet at December 31, 2020 and 2019, was $6.8 million and $4.1 million, respectively. The Company made cash payments during the years ended December 31, 2020, 2019 and 2018 of $14.0 million, $5.0 million and $3.3 million, respectively. The following assumptions were used to determine the grant date fair value of the equity component of the TSR Performance Share Awards for the respective periods: Year Ended December 31, 2020 2019 2018 Fair value per performance share award granted during the period $ 13.79 $ 20.63 $ 19.92 Assumptions Stock price volatility 29.5 % 31.3 % 37.3 % Risk free rate of return 1.4 % 2.5 % 2.4 % The following assumptions were used to determine the fair value of the liability component of the TSR Performance Share Awards for the respective periods: December 31, 2020 2019 2018 Fair value per performance share award at the end of the period $10.37 - $10.81 $6.18 - $14.80 $15.15 - $20.12 Assumptions Stock price volatility 42.4% - 52.4% 29.8% - 30.4% 29.9% - 31.1% Risk free rate of return 0.1% 1.6% 2.5% - 2.6% The stock price volatility was calculated using historical closing stock price data for the Company for the period associated with the expected term through the grant date of each award. The risk free rate of return percentages are based on the continuously compounded equivalent of the U.S. Treasury within the expected term as measured on the grant date. Other Information Compensation expense recorded for both the equity and liability components of all performance share awards for the years ended December 31, 2020, 2019 and 2018 was $39.6 million, $28.8 million and $30.6 million, respectively. Total unamortized compensation expense related to the equity component of performance shares at December 31, 2020 was $28.0 million and will be recognized over the next 2.2 years. As of December 31, 2020, the aggregate intrinsic value for all performance share awards was $63.7 million and was calculated by multiplying the closing market price of the Company's stock on December 31, 2020 by the number of unvested performance share awards outstanding. As of December 31, 2020, the weighted average remaining contractual term of unvested performance share awards outstanding was approximately 1.4 years. On December 31, 2020, the performance period ended for two types of performance share awards that were granted in 2018. For the Employee Performance Share Awards, the calculation of the three-year average of the three internal performance metrics was completed in the first quarter of 2021 and was certified by the Compensation Committee in February 2021. As the Company achieved the three performance metrics, 481,784 shares with a grant date fair value of $11.2 million were issued in February 2021. For the TSR Performance Share Awards, 482,581 shares with a grant date fair value of $9.6 million were issued in December 2020 based on the Company's ranking relative to a predetermined peer group. Cash payments associated with these awards in the amount of $7.9 million were also made in December 2020 due to the Company's ranking relative to the peer group. The calculation of the award payout was certified by the Compensation Committee on December 31, 2020. Deferred Performance Shares As of December 31, 2020, 495,774 shares of the Company's common stock representing vested performance share awards were deferred into the deferred compensation plan. During 2020, no shares were sold out of the plan. During 2020, a decrease to the deferred compensation liability of $0.6 million was recognized, which represents the decrease in the closing price of the Company's shares held in the trust during the period. The decrease in compensation expense was included in general and administrative expense in the Consolidated Statement of Operations.

Earnings per Common Share

Earnings per Common Share	12 Months Ended
Earnings per Common Share	Dec. 31, 2020
Earnings Per Share [Abstract]
Earnings per Common Share	Earnings per Common Share Basic earnings per share (EPS) is computed by dividing net income by the weighted-average number of common shares outstanding for the period. Diluted EPS is similarly calculated except that the common shares outstanding for the period is increased using the treasury stock method to reflect the potential dilution that could occur if outstanding stock awards were vested or exercised at the end of the applicable period. Anti-dilutive shares represent potentially dilutive securities that are excluded from the computation of diluted income or loss per share as their impact would be anti-dilutive. The following is a calculation of basic and diluted weighted-average shares outstanding: Year Ended December 31, (In thousands) 2020 2019 2018 Weighted-average shares - basic 398,521 415,514 445,538 Dilution effect of stock awards at end of period 2,001 1,937 2,030 Weighted-average shares - diluted 400,522 417,451 447,568 The following is a calculation of weighted-average shares excluded from diluted EPS due to the anti-dilutive effect: Year Ended December 31, (In thousands) 2020 2019 2018 Weighted-average stock awards excluded from diluted EPS due to the anti-dilutive effect calculated using the treasury stock method 2 669 3

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	12 Months Ended
Accumulated Other Comprehensive Income	Dec. 31, 2020
Equity [Abstract]
Accumulated Other Comprehensive Income	Accumulated Other Comprehensive Income Changes in accumulated other comprehensive income by component, net of tax, were as follows: (In thousands) Postretirement Balance at December 31, 2017 $ 2,077 Other comprehensive income before reclassifications 2,461 Amounts reclassified from accumulated other comprehensive loss (101) Net current-period other comprehensive income 2,360 Balance at December 31, 2018 $ 4,437 Other comprehensive income before reclassifications (2,530) Amounts reclassified from accumulated other comprehensive loss (547) Net current-period other comprehensive income (3,077) Balance at December 31, 2019 $ 1,360 Other comprehensive income before reclassifications 1,634 Amounts reclassified from accumulated other comprehensive loss (575) Net current-period other comprehensive income 1,059 Balance at December 31, 2020 $ 2,419 Amounts reclassified from accumulated other comprehensive income into the Consolidated Statement of Operations were as follows: Year Ended December 31, Affected Line Item in the (In thousands) 2020 2019 2018 Postretirement benefits Amortization of prior service cost $ 709 $ 709 $ 709 General and administrative expense Amortization of net (gain) loss 36 — — General and administrative expense Total before tax 745 709 709 Income before income taxes Income tax expense (170) (162) (162) Income tax expense Cumulative effect of adoption of ASU 2018-02 reclassified to retained earnings — — (446) Retained earnings Total reclassifications for the period $ 575 $ 547 $ 101 Net income

Additional Balance Sheet Inform

Additional Balance Sheet Information	12 Months Ended
Additional Balance Sheet Information	Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Additional Balance Sheet Information	Additional Balance Sheet Information Certain balance sheet amounts are comprised of the following: December 31, (In thousands) 2020 2019 Accounts receivable, net Trade accounts $ 215,301 $ 209,200 Other accounts 462 1,007 215,763 210,207 Allowance for doubtful accounts (1,039) (1,184) $ 214,724 $ 209,023 Other assets Deferred compensation plan $ 22,510 $ 18,381 Debt issuance cost 6,875 8,938 Operating lease right-of-use assets 33,741 35,916 Other accounts 85 56 $ 63,211 $ 63,291 Accounts payable Trade accounts $ 12,896 $ 21,663 Royalty and other owners 37,243 36,191 Accrued transportation 52,238 55,586 Accrued capital costs 37,872 40,337 Taxes other than income 13,736 16,971 Other accounts 8,096 19,063 $ 162,081 $ 189,811 Accrued liabilities Employee benefits $ 14,270 $ 22,727 Taxes other than income 3,026 3,850 Operating lease liabilities 3,991 3,124 Other accounts 1,087 1,589 $ 22,374 $ 31,290 Other liabilities Deferred compensation plan $ 30,581 $ 27,012 Operating lease liabilities 29,628 32,677 Other accounts 21,069 8,595 $ 81,278 $ 68,284

SUPPLEMENTAL OIL AND GAS INFORM

SUPPLEMENTAL OIL AND GAS INFORMATION (UNAUDITED)	12 Months Ended
SUPPLEMENTAL OIL AND GAS INFORMATION (UNAUDITED)	Dec. 31, 2020
Extractive Industries [Abstract]
SUPPLEMENTAL OIL AND GAS INFORMATION (UNAUDITED)	SUPPLEMENTAL OIL AND GAS INFORMATION (UNAUDITED) Oil and Gas Reserves Users of this information should be aware that the process of estimating quantities of "proved" and "proved developed" natural gas and crude oil reserves is very complex, requiring significant subjective decisions in the evaluation of all available geological, engineering and economic data for each reservoir. The data for a given reservoir may also change substantially over time as a result of numerous factors including, but not limited to, additional development activity, evolving production history and continual reassessment of the viability of production under varying economic conditions. As a result, revisions to existing reserve estimates may occur from time to time. Although every reasonable effort is made to ensure that reserve estimates reported represent the most accurate assessments possible, the subjective decisions and variances in available data for various reservoirs make these estimates generally less precise than other estimates included in the financial statement disclosures. Estimates of total proved reserves at December 31, 2020, 2019 and 2018 were based on studies performed by the Company's petroleum engineering staff. The estimates were computed using the 12-month average index price for the respective commodity, calculated as the unweighted arithmetic average for the first day of the month price for each month during the respective year. The estimates were audited by Miller and Lents, Ltd. (Miller and Lents), who indicated that based on their investigation and subject to the limitations described in their audit letter, they believe the results of those estimates and projections were reasonable in the aggregate. No major discovery or other favorable or unfavorable event after December 31, 2020, is believed to have caused a material change in the estimates of proved or proved developed reserves as of that date. The following tables illustrate the Company's net proved reserves, including changes, and proved developed and proved undeveloped reserves for the periods indicated, as estimated by the Company's engineering staff. All reserves are located within the continental United States. Natural Gas Crude Oil & NGLs (Mbbl) (1) Total (Bcfe) (2) December 31, 2017 9,353 62,252 9,726 Revision of prior estimates (3) 776 677 780 Extensions, discoveries and other additions (4) 2,243 — 2,244 Production (730) (829) (735) Sales of reserves in place (5) (38) (61,980) (410) December 31, 2018 11,604 120 11,605 Revision of prior estimates (6) 48 (48) 47 Extensions, discoveries and other additions (4) 2,116 — 2,116 Production (865) — (865) Sales of reserves in place — (50) — December 31, 2019 12,903 22 12,903 Revision of prior estimates (7) (347) (3) (347) Extensions, discoveries and other additions (4) 1,974 — 1,974 Production (858) (4) (858) December 31, 2020 13,672 15 13,672 Proved Developed Reserves December 31, 2017 6,001 31,066 6,187 December 31, 2018 7,402 107 7,403 December 31, 2019 8,056 22 8,056 December 31, 2020 8,608 15 8,608 Proved Undeveloped Reserves December 31, 2017 3,352 31,186 3,539 December 31, 2018 4,202 13 4,202 December 31, 2019 4,847 — 4,847 December 31, 2020 5,064 — 5,064 _______________________________________________________________________________ (1) There were no significant NGL reserves for 2020, 2019 and 2018. For 2017, NGL reserves were less than one percent of the Company's total proved equivalent reserves and 13.7 percent of the Company's proved crude oil and NGL reserves. (2) Includes natural gas and natural gas equivalents determined by using the ratio of 6 Mcf of natural gas to 1 Bbl of crude oil, condensate or NGLs. (3) The net upward revision of 780 Bcfe was primarily due to an upward revision of 1,123 Bcfe associated with positive drilling results in the Dimock field in northeast Pennsylvania, partially offset by a downward revision of 345 Bcfe associated with proved undeveloped (PUD) reserves reclassifications. (4) Extensions, discoveries and other additions were primarily related to drilling activity in the Dimock field located in northeast Pennsylvania. The Company added 1,974 Bcfe, 2,116 Bcfe and 2,243 Bcfe of proved reserves in this field in 2020, 2019 and 2018, respectively. (5) Sales of reserves in place were primarily related to the divestiture of certain oil and gas properties in the Eagle Ford Shale in February 2018 and the Haynesville Shale in July 2018, which represented 404 Bcfe and 6 Bcfe, respectively. (6) The net upward revision of 47 Bcfe was primarily due to a net upward performance revision of 67 Bcfe, partially offset by a downward revision of 18 Bcfe associated with PUD reclassifications as a result of the five-year limitation. The net upward performance revision of 67 Bcfe was primarily due to an upward revision of 417 Bcfe associated with the Company's PUD reserves due to performance revisions and the drilling of longer lateral length wells, partially offset by a downward performance revision of 350 Bcfe related to certain proved developed producing properties. (7) The net downward revision of 347 Bcfe was primarily due to a net downward performance revision of 245 Bcfe and a downward revision of 66 Bcfe associated with PUD reclassifications as a result of the five-year limitation. The net downward performance revision of 245 Bcfe was primarily due to a downward performance revision of 368 Bcfe related to certain proved developed producing properties, partially offset by an upward revision of 123 Bcfe associated with our PUD reserves due to performance revisions and the drilling of longer lateral length wells. Capitalized Costs Relating to Oil and Gas Producing Activities Capitalized costs relating to oil and gas producing activities and related accumulated depreciation, depletion and amortization were as follows: December 31, (In thousands) 2020 2019 2018 Aggregate capitalized costs relating to oil and gas producing activities $ 7,154,452 $ 6,676,122 $ 5,995,194 Aggregate accumulated depreciation, depletion and amortization (3,148,564) (2,861,014) (2,540,068) Net capitalized costs $ 4,005,888 $ 3,815,108 $ 3,455,126 Costs Incurred in Oil and Gas Property Acquisition, Exploration and Development Activities Costs incurred in property acquisition, exploration and development activities were as follows: Year Ended December 31, (In thousands) 2020 2019 2018 Property acquisition costs, proved $ — $ — $ — Property acquisition costs, unproved 5,821 6,072 29,851 Exploration costs 15,419 20,270 94,309 Development costs 546,646 761,326 778,574 Total costs $ 567,886 $ 787,668 $ 902,734 Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves The following information has been developed based on natural gas and crude oil reserve and production volumes estimated by the Company's engineering staff. It can be used for some comparisons, but should not be the only method used to evaluate the Company or its performance. Further, the information in the following table may not represent realistic assessments of future cash flows, nor should the Standardized Measure of Discounted Future Net Cash Flows (Standardized Measure) be viewed as representative of the current value of the Company. The Company believes that the following factors should be taken into account when reviewing the following information: • Future costs and selling prices will differ from those required to be used in these calculations. • Due to future market conditions and governmental regulations, actual rates of production in future years may vary significantly from the rate of production assumed in the calculations. • Selection of a 10 percent discount rate is arbitrary and may not be a reasonable measure of the relative risk that is part of realizing future net oil and gas revenues. • Future net revenues may be subject to different rates of income taxation. Under the Standardized Measure, future cash inflows were estimated by using the 12-month average index price for the respective commodity, calculated as the unweighted arithmetic average for the first day of the month price for each month during the year. The average prices (adjusted for basis and quality differentials) related to proved reserves are as follows: Year Ended December 31, 2020 2019 2018 Natural gas $ 1.64 $ 2.35 $ 2.58 Crude oil $ 32.53 $ 55.80 $ 65.21 NGLs $ — $ — $ 21.64 In the above table, natural gas prices are stated per Mcf and crude oil and NGL prices are stated per barrel. Future cash inflows were reduced by estimated future development and production costs based on year end costs to arrive at net cash flow before tax. Future income tax expense was computed by applying year end statutory tax rates to future pretax net cash flows, less the tax basis of the properties involved and utilization of available tax carryforwards related to oil and gas operations. The applicable accounting standards require the use of a 10 percent discount rate. Management does not solely use the following information when making investment and operating decisions. These decisions are based on a number of factors, including estimates of proved reserves, and varying price and cost assumptions considered more representative of a range of anticipated economic conditions. Standardized Measure is as follows: Year Ended December 31, (In thousands) 2020 2019 2018 Future cash inflows $ 22,385,385 $ 30,302,480 $ 29,904,474 Future production costs (10,783,895) (10,039,294) (8,702,734) Future development costs (1) (1,612,659) (2,006,167) (1,766,796) Future income tax expenses (2,175,916) (4,042,787) (4,166,089) Future net cash flows 7,812,915 14,214,232 15,268,855 10% annual discount for estimated timing of cash flows (4,750,760) (8,353,115) (8,785,547) Standardized measure of discounted future net cash flows $ 3,062,155 $ 5,861,117 $ 6,483,308 ______________________________________________________________________________ (1) Includes $223.7 million, $212.9 million and $193.5 million in plugging and abandonment costs for the years ended December 31, 2020, 2019 and 2018, respectively. Changes in Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves The following is an analysis of the changes in the Standardized Measure: Year Ended December 31, (In thousands) 2020 2019 2018 Beginning of year $ 5,861,117 $ 6,483,308 $ 5,010,446 Discoveries and extensions, net of related future costs 311,336 1,075,839 1,280,499 Net changes in prices and production costs (4,326,254) (1,510,104) 2,078,479 Accretion of discount 750,041 813,480 596,569 Revisions of previous quantity estimates (107,467) 28,310 586,494 Timing and other 5,992 (192,563) (76,761) Development costs incurred 501,093 468,748 338,297 Sales and transfers, net of production costs (746,310) (1,316,752) (1,343,872) Sales of reserves in place — (1,350) (1,290,594) Net change in income taxes 812,607 12,201 (696,249) End of year $ 3,062,155 $ 5,861,117 $ 6,483,308

QUARTERLY FINANCIAL INFORMATION

QUARTERLY FINANCIAL INFORMATION (UNAUDITED)	12 Months Ended
QUARTERLY FINANCIAL INFORMATION (UNAUDITED)	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
QUARTERLY FINANCIAL INFORMATION (UNAUDITED)	CABOT OIL & GAS CORPORATION SELECTED DATA QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (In thousands, except per share amounts) First Second Third Fourth Total 2020 Operating revenues $ 386,457 $ 332,348 $ 291,041 $ 456,778 $ 1,466,624 Operating income (loss) 86,401 53,716 (7,533) 162,892 295,476 Net income (loss) 53,910 30,374 (14,961) 131,206 200,529 Basic earnings (loss) per share 0.14 0.08 (0.04) 0.33 0.50 Diluted earnings (loss) per share 0.13 0.08 (0.04) 0.33 0.50 2019 Operating revenues $ 641,681 $ 534,117 $ 429,111 $ 461,368 $ 2,066,277 Earnings on equity method investments (1) 3,684 3,650 3,860 69,302 80,496 Operating income 352,959 250,805 129,777 222,209 955,750 Net income 262,763 181,009 90,358 146,940 681,070 Basic earnings per share 0.62 0.43 0.22 0.36 1.64 Diluted earnings per share 0.62 0.43 0.22 0.36 1.63 _______________________________________________________________________________ (1) Earnings on equity method investments in the fourth quarter of 2019 includes a gain on sale of $75.8 million associated with the Company's sale of its equity investment in Meade.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Nature of Operations	Basis of Presentation and Nature of Operations Cabot Oil & Gas Corporation and its subsidiaries (the Company) are engaged in the development, exploitation, exploration, production and marketing of natural gas exclusively within the continental United States. The Company's exploration and development activities are concentrated in areas with known hydrocarbon resources, which are conducive to multi-well, repeatable drilling programs. The Company operates in one segment, natural gas development, exploitation, exploration and production. The Company's oil and gas properties are managed as a whole rather than through discrete operating segments or business units. Operational information is tracked by geographic area; however, financial performance is assessed as a single enterprise and not on a geographic basis. Allocation of resources is made on a project basis across the Company's entire portfolio without regard to geographic areas. The consolidated financial statements include the accounts of the Company and its subsidiaries after eliminating all significant intercompany balances and transactions. Certain reclassifications have been made to prior year statements to conform with the current year presentation. These reclassifications have no impact on previously reported stockholders' equity, net income or cash flows.
Recently Adopted / Issued Accounting Pronouncements	Recently Adopted Accounting Pronouncements Financial Instruments: Credit Losses. In June 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2016-13, Financial Instruments: Credit Losses, which replaces the incurred loss impairment methodology used for certain financial instruments with a methodology that reflects current expected credit losses (CECL). ASU No. 2016-13, along with subsequently issued codification improvements, was effective for the Company on January 1, 2020, and was applied using a modified retrospective approach. The Company's historical credit losses have not been material, and future expected credit losses under the CECL model are not expected to be material. The adoption of ASU No. 2016-13 did not have a material effect on the Company's financial position, results of operations or cash flows; however, it modified certain disclosure requirements, which were not material. Fair Value Measurements. In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement, which modifies the disclosure requirements by adding, removing and modifying certain required disclosures for fair value measurements for assets and liabilities disclosed within the fair value hierarchy. The Company adopted ASU No. 2018-13 effective January 1, 2020. The adoption of ASU No. 2018-13 did not have any effect on the Company's financial position, results of operations or cash flows; however, it modified certain disclosure requirements, which were not material.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid short-term investments with a maturity of three months or less and deposits in money market funds that are readily convertible to cash to be cash equivalents. Cash and cash equivalents were primarily concentrated in one financial institution at December 31, 2020. The Company periodically assesses the financial condition of its financial institutions and considers any possible credit risk to be minimal. From time to time, the Company may be in the position of a book overdraft in which outstanding checks exceed cash and cash equivalents. The Company classifies book overdrafts in accounts payable in the Consolidated Balance Sheet, and classifies the change in accounts payable associated with book overdrafts as an operating activity in the Consolidated Statement of Cash Flows. There was no book overdraft within accounts payable as of December 31, 2020 and 2019.
Restricted Cash	Restricted Cash.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts The Company records an allowance for doubtful accounts based on the Company's estimate of future expected credit losses on outstanding receivables.
Inventories	Inventories Inventories are comprised of tubular goods and well equipment and are carried at average cost.
Equity Method Investments	Equity Method Investments The Company accounts for its investments in entities over which the Company has significant influence, but not control, using the equity method of accounting. Under the equity method of accounting, the Company increases its investment for contributions made and records its proportionate share of net earnings, declared dividends and partnership distributions based on the most recently available financial statements of the investee. The Company records the activity for its equity method investments on a one month lag. In addition, the Company evaluates its equity method investments for potential impairment whenever events or changes in circumstances indicate that there is a decline in the value of the investment.
Properties and Equipment	Properties and Equipment The Company uses the successful efforts method of accounting for oil and gas producing activities. Under this method, acquisition costs for proved and unproved properties are capitalized when incurred. Exploration costs, including geological and geophysical costs, the costs of carrying and retaining unproved properties and exploratory dry hole drilling costs, are expensed. Development costs, including the costs to drill and equip development wells and successful exploratory drilling costs to locate proved reserves are capitalized. Exploratory drilling costs are capitalized when incurred pending the determination of whether a well has found proved reserves. The determination is based on a process which relies on interpretations of available geologic, geophysical, and engineering data. If a well is determined to be successful, the capitalized drilling costs will be reclassified as part of the cost of the well. If a well is determined to be unsuccessful, the capitalized drilling costs will be charged to exploration expense in the Consolidated Statement of Operations in the period the determination is made. If an exploratory well requires a major capital expenditure before production can begin, the cost of drilling the exploratory well will continue to be carried as an asset pending determination of whether reserves have been found only as long as: (i) the well has found a sufficient quantity of reserves to justify its completion as a producing well if the required capital expenditure is made and (ii) drilling of an additional exploratory well is under way or firmly planned for the near future. If drilling in the area is not under way or firmly planned, or if the well has not found a commercially producible quantity of reserves, the exploratory well is assumed to be impaired and its costs are charged to exploration expense. Development costs of proved oil and gas properties, including estimated dismantlement, restoration and abandonment costs and acquisition costs, are depreciated and depleted on a field basis by the units-of-production method using proved developed and proved reserves, respectively. Buildings are depreciated on a straight-line basis over 25 to 40 years. Certain other assets are depreciated on a straight-line basis over 3 to 25 years. Costs of sold or abandoned properties that make up a part of an amortization base (partial field) remain in the amortization base if the units-of-production rate is not significantly affected. If significant, a gain or loss, if any, is recognized and the sold or abandoned properties are retired. A gain or loss, if any, is also recognized when a group of proved properties (entire field) that make up the amortization base has been retired, abandoned or sold. The Company evaluates its proved oil and gas properties for impairment whenever events or changes in circumstances indicate an asset's carrying amount may not be recoverable. The Company compares expected undiscounted future cash flows to the net book value of the asset. If the future undiscounted expected cash flows, based on estimates of future commodity prices, operating costs and anticipated production from proved reserves and risk-adjusted probable and possible reserves, are lower than the net book value of the asset, the capitalized cost is reduced to fair value. Commodity pricing is estimated by using a combination of assumptions management uses in its budgeting and forecasting process as well as historical and current prices adjusted for geographical location and quality differentials, as well as other factors that management believes will impact realizable prices. Fair value is calculated by discounting the future cash flows. The discount factor used is based on rates utilized by market participants that are commensurate with the risks inherent in the development and production of the underlying natural gas and oil. Unproved oil and gas properties are assessed periodically for impairment on an aggregate basis through periodic updates to the Company's undeveloped acreage amortization based on past drilling and exploration experience, the Company's expectation of converting leases to held by production and average property lives. Average property lives are determined on a geographical basis and based on the estimated life of unproved property leasehold rights. During 2020, 2019 and 2018, amortization associated with the Company's unproved properties was $8.2 million, $32.6 million and $82.3 million, respectively, and is included in depreciation, depletion, and amortization in the Consolidated Statement of Operations.
Asset Retirement Obligations	Asset Retirement Obligations The Company records the fair value of a liability for an asset retirement obligation in the period in which it is incurred if a reasonable estimate of fair value can be made. The associated asset retirement cost is capitalized as part of the carrying amount of the long-lived asset. The asset retirement costs are depreciated using the units-of-production method. At December 31, 2020 and 2019, there were no assets legally restricted for purposes of settling asset retirement obligations. Additional retirement obligations increase the liability associated with new oil and gas wells and other facilities as these obligations are incurred. Accretion expense is included in depreciation, depletion and amortization expense in the Consolidated Statement of Operations.
Derivative Instruments	Derivative Instruments The Company enters into financial derivative contracts, primarily swaps, collars and basis swaps, to manage its exposure to price fluctuations on a portion of its anticipated future production volumes. The Company’s credit agreement restricts the ability of the Company to enter into commodity derivatives other than to hedge or mitigate risks to which the Company has actual or projected exposure or as permitted under the Company’s risk management policies and where such derivatives do not subject the Company to material speculative risks. All of the Company’s derivatives are used for risk management purposes and are not held for trading purposes. The Company has elected not to designate its financial derivative instruments as accounting hedges under the accounting guidance. The Company evaluates all of its physical purchase and sale contracts to determine if they meet the definition of a derivative. For contracts that meet the definition of a derivative, the Company may elect the normal purchase normal sale (NPNS) exception provided under the accounting guidance and account for the contract using the accrual method of accounting. Contracts that do not qualify for or for which the Company elects not to apply the NPNS exception are accounted for at fair value. All derivatives, except for derivatives that qualify for the NPNS exception, are recognized on the balance sheet and are measured at fair value. At the end of each quarterly period, these derivatives are marked to market. As a result, changes in the fair value of derivatives are recognized in operating revenues in gain (loss) on derivative instruments. The resulting cash flows are reported as cash flows from operating activities.
Leases	Leases The Company determines if an arrangement is, or contains, a lease at inception based on whether that contract conveys the right to control the use of an identified asset in exchange for consideration for a period of time. Operating leases are included in operating lease right-of-use assets (ROU assets) and operating lease liabilities (current and non-current) in the Consolidated Balance Sheet. The Company did not have any finance leases at December 31, 2020 and 2019. ROU assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the leases. ROU assets and lease liabilities are recognized at the lease commencement date based on the present value of minimum lease payments over the lease term. Most leases do not provide an implicit interest rate; therefore, the Company used its incremental borrowing rate based on the information available at the inception date to determine the present value of the lease payments. Lease terms include options to extend the lease when it is reasonably certain that the Company will exercise that option. Lease cost for lease payments is recognized on a straight-line basis over the lease term. Certain leases have payment terms that vary based on the usage of the underlying assets. Variable lease payments are not included in ROU assets and lease liabilities. The Company has elected the following practical expedients in applying authoritative guidance on lease accounting: • For all operating leases, lease and non-lease components are accounted for as a single lease component. • Short-term leases (a lease that, at commencement, has a lease term of one year or less and does not contain a purchase option that the Company is reasonably certain to exercise) have not be recognized in ROU assets and lease liabilities.
Fair Value of Assets and Liabilities	Fair Value of Assets and Liabilities The Company follows the authoritative accounting guidance for measuring fair value of assets and liabilities in its financial statements. Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). The Company utilizes market data or assumptions that market participants who are independent, knowledgeable and willing and able to transact would use in pricing the asset or liability, including assumptions about risk and the risks inherent in the inputs to the valuation technique. The Company is able to classify fair value balances based on the observability of these inputs. The authoritative guidance for fair value measurements establishes three levels of the fair value hierarchy, defined as follows: • Level 1: Unadjusted, quoted prices for identical assets or liabilities in active markets. • Level 2: Quoted prices in markets that are not considered to be active or financial instruments for which all significant inputs are observable, either directly or indirectly for substantially the full term of the asset or liability. • Level 3: Significant, unobservable inputs for use when little or no market data exists, requiring a significant degree of judgment. The hierarchy gives the highest priority to Level 1 measurements and the lowest priority to Level 3 measurements. Depending on the particular asset or liability, input availability can vary depending on factors such as product type, longevity of a product in the market and other particular transaction conditions. In some cases, certain inputs used to measure fair value may be categorized into different levels of the fair value hierarchy. For disclosure purposes under the accounting guidance, the lowest level that contains significant inputs used in the valuation should be chosen.
Revenue Recognition	Revenue Recognition The Company’s revenue is typically generated from contracts to sell natural gas produced from interests in oil and gas properties owned by the Company. These contracts generally require the Company to deliver a specific amount of a commodity per day for a specified number of days at a price that is either fixed or variable. The contracts specify a delivery point which represents the point at which control of the product is transferred to the customer. These contracts frequently meet the definition of a derivative under ASC 815, and are accounted for as derivatives unless the Company elects to treat them as normal sales as permitted under that guidance. The Company typically elects to treat contracts to sell oil and gas production as normal sales, which are then accounted for as contracts with customers. The Company has determined that these contracts represent multiple performance obligations which are satisfied when control of the commodity transfers to the customer, typically through the delivery of the specified commodity to a designated delivery point. Revenue is measured based on consideration specified in the contract with the customer, and excludes any amounts collected on behalf of third parties. The Company recognizes revenue in the amount that reflects the consideration it expects to be entitled to in exchange for transferring control of those goods to the customer. The contract consideration in the Company’s variable price contracts are typically allocated to specific performance obligations in the contract according to the price stated in the contract. Amounts allocated in the Company’s fixed price contracts are based on the standalone selling price of those products in the context of long-term, fixed price contracts, which generally approximates the contract price. Payment is generally received one or two months after the sale has occurred. Gain or loss on derivative instruments is outside the scope of the revenue recognition standard and is not considered revenue from contracts with customers under that guidance. The Company may use financial or physical contracts accounted for as derivatives as economic hedges to manage price risk associated with normal sales, or in limited cases may use them for contracts the Company intends to physically settle but do not meet all of the criteria to be treated as normal sales. Taxes assessed by a governmental authority that are both imposed on and concurrent with a specific revenue-producing transaction, and that are collected by the Company from a customer, are excluded from revenue. Producer Gas Imbalances. The Company applies the sales method of accounting for natural gas revenue. Under this method, revenues are recognized based on the actual volume of natural gas sold to purchasers. Natural gas production operations may include joint owners who take more or less than the production volumes entitled to them on certain properties. Production volume is monitored to minimize these natural gas imbalances. Under this method, a natural gas imbalance liability is recorded if the Company's excess takes of natural gas exceed its estimated remaining proved developed reserves for these properties at the actual price realized upon the gas sale. A receivable is recognized only to the extent an imbalance cannot be recouped from the reserves in the underlying properties. The Company’s aggregate imbalance positions at December 31, 2020 and 2019 were not material. Brokered Natural Gas. Revenues and expenses related to brokered natural gas are reported gross as part of operating revenues and operating expenses in accordance with applicable accounting standards. The Company buys and sells natural gas utilizing separate purchase and sale transactions whereby the Company or the counterparty obtains control of the natural gas purchased or sold. Practical Expedients. The Company makes use of certain practical expedients provided under the revenue standard, including the value of unsatisfied performance obligations are not disclosed for (i) contracts with an original expected length of one year or less, (ii) contracts for which the Company recognizes revenue at the amount to which the Company has the right to invoice, (iii) contracts with variable consideration which is allocated entirely to a wholly unsatisfied performance obligation and meets the variable allocation criteria in the standard and (iv) contracts that were not completed at transition.
Income Taxes	Income Taxes The Company follows the asset and liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are recorded for the estimated future tax consequences attributable to the differences between the financial carrying amounts of existing assets and liabilities and their respective tax basis. Deferred tax assets and liabilities are measured using the tax rate in effect for the year in which those temporary differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in the year of the enacted rate change. A valuation allowance is established to reduce deferred tax assets if it is more likely than not that the related tax benefits will not be realized. The Company follows the “equity first” approach when applying the limitation for certain executive compensation in excess of $1 million to future compensation. The limitation is first applied to stock-based compensation that vests in future tax years before considering cash compensation paid in a future period. Accordingly, the Company records a deferred tax asset for stock-based compensation expense recorded in the current period, and reverses the temporary difference in the future period, during which the stock-based compensation becomes deductible for tax purposes. The Company is required to make judgments, including estimating reserves for potential adverse outcomes regarding tax positions that the Company has taken. The Company accounts for uncertainty in income taxes using a recognition and measurement threshold for tax positions taken or expected to be taken in a tax return. The tax benefit from an uncertain tax position is recognized when it is more likely than not that the position will be sustained upon examination by taxing authorities based on technical merits of the position. The amount of the tax benefit recognized is the largest amount of the benefit that has a greater than 50 percent likelihood of being realized upon ultimate settlement. The effective tax rate and the tax basis of assets and liabilities reflect management's estimates of the ultimate outcome of various tax uncertainties. The Company recognizes accrued interest related to uncertain tax positions in interest expense and accrued penalties related to such positions in general and administrative expense in the Consolidated Statement of Operations.
Stock-Based Compensation	Stock-Based Compensation The Company accounts for stock-based compensation under the fair value method of accounting. Under this method, compensation cost is measured at the grant date for equity-classified awards and remeasured each reporting period for liability-classified awards based on the fair value of an award and is recognized over the service period, which is generally the vesting period. To calculate fair value, the Company uses a Monte Carlo valuation model based on the specific provisions of the award. Stock-based compensation cost for all types of awards is included in general and administrative expense in the Consolidated Statement of Operations. The Company records excess tax benefits and tax deficiencies on stock-based compensation in the income statement upon vesting of the respective awards. Excess tax benefits and tax deficiencies are included in cash flows from operating activities in the Consolidated Statement of Cash Flow. Cash paid by the Company when directly withholding shares from employee stock-based compensation awards for tax-withholding purposes are classified as financing activities in the Consolidated Statement of Cash Flow.
Environmental Matters	Environmental Matters Environmental expenditures are expensed or capitalized, as appropriate, depending on their future economic benefit. Expenditures that relate to an existing condition caused by past operations, and that do not have future economic benefit are expensed. Liabilities related to future costs are recorded on an undiscounted basis when environmental assessments and/or remediation activities are probable and the costs can be reasonably estimated. Any insurance recoveries are recorded as assets when received.
Credit and Concentration Risk	Credit and Concentration Risk Substantially all of the Company's accounts receivable result from the sale of natural gas to third parties in the oil and gas industry. This concentration of purchasers may impact the Company's overall credit risk, either positively or negatively, in that these entities may be similarly affected by changes in economic or other conditions. The Company does not anticipate any material impact on its financial results due to non-performance by the third parties.
Use of Estimates	Use of Estimates In preparing financial statements, the Company follows accounting principles generally accepted in the United States. These principles require management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. The most significant estimates pertain to proved natural gas reserves and related cash flow estimates which are used to compute depreciation, depletion and amortization and impairments of proved oil and gas properties. Other significant estimates include natural gas revenues and expenses, fair value of derivative instruments, estimates of expenses related to legal, environmental and other contingencies, asset retirement obligations, postretirement obligations, stock-based compensation and deferred income taxes. Actual results could differ from those estimates.

Properties and Equipment, Net (

Properties and Equipment, Net (Tables)	12 Months Ended
Properties and Equipment, Net (Tables)	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Components of Properties and Equipment, Net	Properties and equipment, net are comprised of the following: December 31, (In thousands) 2020 2019 Proved oil and gas properties $ 7,068,605 $ 6,508,443 Unproved oil and gas properties 49,829 133,475 Land, buildings and other equipment 92,566 104,700 7,211,000 6,746,618 Accumulated depreciation, depletion and amortization (3,166,394) (2,890,912) $ 4,044,606 $ 3,855,706
Schedule of Net Changes in Capitalized Exploratory Well Costs	The following table reflects the net changes in capitalized exploratory well costs: Year Ended December 31, (In thousands) 2020 2019 2018 Balance at beginning of period $ — $ — $ 19,511 Additions to capitalized exploratory well costs pending the — — — Reclassifications to wells, facilities, and equipment based on the — — — Capitalized exploratory well costs charged to expense — — (19,511) Balance at end of period $ — $ — $ —
Schedule of Aging of Capitalized Exploratory Well Costs	The following table provides an aging of capitalized exploratory well costs based on the date the drilling was completed: December 31, (In thousands) 2020 2019 2018 Capitalized exploratory well costs that have been capitalized for a period of one year or less $ — $ — $ — Capitalized exploratory well costs that have been capitalized for a period greater than one year — — — $ — $ — $ —

Equity Method Investments (Tabl

Equity Method Investments (Tables)	12 Months Ended
Equity Method Investments (Tables)	Dec. 31, 2020
Equity Method Investments and Joint Ventures [Abstract]
Activity Related to Equity Method Investments	Activity related to the Company's equity method investments is as follows: Constitution Meade Total Year Ended December 31, Year Ended December 31, Year Ended December 31, (In thousands) 2020 2019 2018 2020 2019 2018 2020 2019 2018 Balance at beginning of period $ — $ — $ 732 $ — $ 163,181 $ 85,345 $ — $ 163,181 $ 86,077 Contributions 35 725 500 — 8,613 76,763 35 9,338 77,263 Distributions — — — — (17,453) (1,296) — (17,453) (1,296) (Loss) earnings on equity method investments (35) (10,125) (1,232) (24) 90,621 2,369 (59) 80,496 1,137 Reclassification of accumulated losses (1) — 9,400 — — — — — 9,400 — Sale of investment — — — 24 (244,962) — 24 (244,962) — Balance at end of period $ — $ — $ — $ — $ — $ 163,181 $ — $ — $ 163,181 ______________________________________________________________________________ (1) Amount was included in accounts payable in the Consolidated Balance Sheet as of December 31, 2019.

Debt and Credit Agreements (Tab

Debt and Credit Agreements (Tables)	12 Months Ended
Debt and Credit Agreements (Tables)	Dec. 31, 2020
Debt Disclosure [Abstract]
Schedule of Long-term Debt and Credit Agreements	The Company's debt and credit agreements consisted of the following: December 31, (In thousands) 2020 2019 Total debt 6.51% weighted-average senior notes (1) $ 37,000 $ 124,000 5.58% weighted-average senior notes (2) 175,000 175,000 3.65% weighted-average senior notes (3) 925,000 925,000 Revolving credit facility — — Unamortized debt issuance costs (3,076) (3,975) $ 1,133,924 $ 1,220,025 _______________________________________________________________________________ (1) Includes $87.0 million of current portion of long-term debt at December 31, 2019, which the Company repaid in July 2020. (2) Includes $88.0 million of current portion of long-term debt at December 31, 2020, which the Company repaid in January 2021. (3) Includes $100.0 million of current portion of long-term debt at December 31, 2020 due in September 2021. Principal Term Maturity Coupon Tranche 1 $ 245,000,000 10 years July 2018 6.44 % Tranche 2 $ 100,000,000 12 years July 2020 6.54 % Tranche 3 $ 80,000,000 15 years July 2023 6.69 % Principal Term Maturity Coupon Tranche 1 $ 88,000,000 10 years January 2021 5.42 % Tranche 2 $ 25,000,000 12 years January 2023 5.59 % Tranche 3 $ 62,000,000 15 years January 2026 5.80 % Principal Term Maturity Date Coupon Tranche 1 $ 100,000,000 7 years September 2021 3.24 % Tranche 2 $ 575,000,000 10 years September 2024 3.67 % Tranche 3 $ 250,000,000 12 years September 2026 3.77 %

Derivative Instruments (Tables)

Derivative Instruments (Tables)	12 Months Ended
Derivative Instruments (Tables)	Dec. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of Outstanding Financial Commodity Derivatives	As of December 31, 2020, the Company had the following outstanding financial commodity derivatives: Collars Floor Ceiling Swaps Type of Contract Volume (Mmbtu) Contract Period Range Weighted-Average Range Weighted- Average Weighted- Average Natural gas (NYMEX) 18,250,000 Jan. 2021-Dec. 2021 $ 2.74 Natural gas (NYMEX) 164,250,000 Jan. 2021-Dec. 2021 $2.50 - $2.85 $ 2.68 $2.83 - $3.94 $ 3.09 Natural gas (NYMEX) 10,700,000 Apr. 2021-Oct. 2021 $ — $ 2.50 $ — $ 2.80 Natural gas (NYMEX) 10,700,000 Apr. 2021-Oct. 2021 $ 2.75 In early 2021, the Company entered into the following financial commodity derivatives: Swaps Type of Contract Volume (Mmbtu) Contract Period Weighted- Average ($/Mmbtu) Natural gas (NYMEX) 10,700,000 Apr. 2021-Oct. 2021 $ 2.81
Effect of Derivative Instruments on Consolidated Balance Sheet	Effect of Derivative Instruments on the Consolidated Balance Sheet Fair Values of Derivative Instruments Derivative Assets Derivative Liabilities December 31, December 31, (In thousands) Balance Sheet Location 2020 2019 2020 2019 Commodity contracts Derivative instruments (current) $ 26,209 $ 31 $ — $ — Commodity contracts Accrued liabilities — — — 9
Schedule of Offsetting Derivative Assets in Consolidated Balance Sheet	Offsetting of Derivative Assets and Liabilities in the Consolidated Balance Sheet December 31, (In thousands) 2020 2019 Derivative assets Gross amounts of recognized assets $ 26,354 $ 47 Gross amounts offset in the consolidated balance sheet (145) (16) Net amounts of assets presented in the consolidated balance sheet 26,209 31 Gross amounts of financial instruments not offset in the consolidated balance sheet — — Net amount $ 26,209 $ 31 Derivative liabilities Gross amounts of recognized liabilities $ 145 $ 25 Gross amounts offset in the consolidated balance sheet (145) (16) Net amounts of liabilities presented in the consolidated balance sheet — 9 Gross amounts of financial instruments not offset in the consolidated balance sheet — — Net amount $ — $ 9
Schedule of Offsetting Derivative Liabilities in Consolidated Balance Sheet	Offsetting of Derivative Assets and Liabilities in the Consolidated Balance Sheet December 31, (In thousands) 2020 2019 Derivative assets Gross amounts of recognized assets $ 26,354 $ 47 Gross amounts offset in the consolidated balance sheet (145) (16) Net amounts of assets presented in the consolidated balance sheet 26,209 31 Gross amounts of financial instruments not offset in the consolidated balance sheet — — Net amount $ 26,209 $ 31 Derivative liabilities Gross amounts of recognized liabilities $ 145 $ 25 Gross amounts offset in the consolidated balance sheet (145) (16) Net amounts of liabilities presented in the consolidated balance sheet — 9 Gross amounts of financial instruments not offset in the consolidated balance sheet — — Net amount $ — $ 9
Effect of Derivative Instruments on Consolidated Statement of Operations	Effect of Derivative Instruments on the Consolidated Statement of Operations Year Ended December 31, (In thousands) 2020 2019 2018 Cash received (paid) on settlement of derivative instruments Gain (loss) on derivative instruments $ 35,218 $ 138,450 $ (41,631) Non-cash gain (loss) on derivative instruments Gain (loss) on derivative instruments 26,186 (57,642) 86,063 $ 61,404 $ 80,808 $ 44,432

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
Fair Value Measurements (Tables)	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Summary of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis	The following fair value hierarchy table presents information about the Company's financial assets and liabilities measured at fair value on a recurring basis: (In thousands) Quoted Prices in Significant Other Significant Balance at Assets Deferred compensation plan $ 22,510 $ — $ — $ 22,510 Derivative instruments — 2,647 23,707 26,354 Total assets $ 22,510 $ 2,647 $ 23,707 $ 48,864 Liabilities Deferred compensation plan $ 30,581 $ — $ — $ 30,581 Derivative instruments — — 145 145 Total liabilities $ 30,581 $ — $ 145 $ 30,726 (In thousands) Quoted Prices in Significant Other Significant Balance at Assets Deferred compensation plan $ 18,381 $ — $ — $ 18,381 Derivative instruments — 44 3 47 Total assets $ 18,381 $ 44 $ 3 $ 18,428 Liabilities Deferred compensation plan $ 27,012 $ — $ — $ 27,012 Derivative instruments — — 25 25 Total liabilities $ 27,012 $ — $ 25 $ 27,037
Reconciliation of Changes in Fair Value of Financial Assets and Liabilities Classified as Level 3	The following table sets forth a reconciliation of changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy: Year Ended December 31, (In thousands) 2020 2019 2018 Balance at beginning of period $ (22) $ 21,976 $ (28,398) Total gain (loss) included in earnings 40,563 24,794 31,184 Settlement (gain) loss (16,979) (46,792) 19,190 Transfers in and/or out of Level 3 — — — Balance at end of period $ 23,562 $ (22) $ 21,976 Change in unrealized gains (losses) relating to assets and liabilities still held at the end of the period $ 23,562 $ (22) $ 19,732
Carrying Amount and Fair Value of Debt	The carrying amount and fair value of debt is as follows: December 31, 2020 December 31, 2019 (In thousands) Carrying Estimated Carrying Estimated Long-term debt $ 1,133,924 $ 1,213,811 $ 1,220,025 $ 1,260,259 Current maturities (188,000) (189,332) (87,000) (88,704) Long-term debt, excluding current maturities $ 945,924 $ 1,024,479 $ 1,133,025 $ 1,171,555

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	12 Months Ended
Asset Retirement Obligations (Tables)	Dec. 31, 2020
Asset Retirement Obligation Disclosure [Abstract]
Activity Related to Asset Retirement Obligations	Activity related to the Company's asset retirement obligations is as follows: Year Ended December 31, (In thousands) 2020 2019 Balance at beginning of period $ 72,098 $ 51,622 Liabilities incurred 10,008 7,646 Liabilities settled (322) (1,467) Accretion expense 4,205 3,430 Change in estimate — 10,867 Balance at end of period 85,989 72,098 Less: current asset retirement obligation (500) (500) Noncurrent asset retirement obligation $ 85,489 $ 71,598

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
Commitments and Contingencies (Tables)	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Future Minimum Obligations under Transportation and Gathering Agreements	As of December 31, 2020, the Company's future minimum obligations under transportation and gathering agreements are as follows: (In thousands) 2021 $ 105,304 2022 191,455 2023 185,913 2024 179,772 2025 169,050 Thereafter 1,184,624 $ 2,016,118
Future Undiscounted Minimum Cash Payment Obligations for Operating Lease Liabilities	As of December 31, 2020, the Company’s future undiscounted minimum cash payment obligations for its operating lease liabilities are as follows: (In thousands) Year Ending December 31, 2021 $ 5,556 2022 4,894 2023 4,613 2024 4,653 2025 4,675 Thereafter 20,495 Total undiscounted future lease payments 44,886 Present value adjustment (11,267) Net operating lease liabilities $ 33,619
Supplemental Cash Flow Information Related to Leases	Supplemental cash flow information related to leases was as follows: Year Ended December 31, (In thousands) 2020 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 5,338 $ 4,614 Investing cash flows from operating leases $ — $ 6,647 Information regarding the weighted-average remaining lease term and the weighted-average discount rate for operating leases is summarized below: December 31, 2020 2019 Weighted-average remaining lease term (in years) Operating leases 11.1 12.1 Weighted-average discount rate Operating leases 5.0 % 5.0 %

Revenue Recognition (Tables)

Revenue Recognition (Tables)	12 Months Ended
Revenue Recognition (Tables)	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Revenues from Contracts with Customers Disaggregated by Product	The following table presents revenues from contracts with customers disaggregated by product: Year Ended December 31, (In thousands) 2020 2019 2018 OPERATING REVENUES Natural gas $ 1,404,989 $ 1,985,240 $ 1,881,150 Crude oil and condensate — — 48,722 Brokered natural gas — — 209,530 Other 231 229 4,314 Total revenues from contracts with customers $ 1,405,220 $ 1,985,469 $ 2,143,716

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
Income Taxes (Tables)	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Summary of Income Tax Expense (Benefit)	Income tax expense is summarized as follows: Year Ended December 31, (In thousands) 2020 2019 2018 Current Federal $ (31,838) $ (29,584) $ (95,191) State 655 4,320 6,682 (31,183) (25,264) (88,509) Deferred Federal 67,451 233,136 230,643 State 4,326 11,282 (1,040) 71,777 244,418 229,603 Income tax expense $ 40,594 $ 219,154 $ 141,094
Schedule of Reconciliation of Income Tax Expense (Benefit) Computed by Applying Statutory Federal Income Tax Rate	Income tax expense was different than the amounts computed by applying the statutory federal income tax rate as follows: Year Ended December 31, 2020 2019 2018 (In thousands, except rates) Amount Rate Amount Rate Amount Rate Computed "expected" federal income tax $ 50,636 21.00 % $ 189,047 21.00 % $ 146,609 21.00 % State income tax, net of federal income tax benefit 4,486 1.86 % 14,773 1.64 % 11,850 1.70 % Deferred tax adjustment related to change in overall state tax rate 1,213 0.50 % (660) (0.07) % (15,208) (2.18) % Valuation allowance (3,800) (1.58) % 17,676 1.96 % 8,975 1.29 % Excess executive compensation 5,249 2.18 % 1,935 0.21 % 1,382 0.20 % Reserve on uncertain tax positions 5,964 2.47 % 5 — % — — % Tax credits generated (23,216) (9.63) % — — % — — % Tax Act — — % — — % (11,367) (1.63) % Other, net 62 0.04 % (3,622) (0.40) % (1,147) (0.16) % Income tax expense $ 40,594 16.84 % $ 219,154 24.34 % $ 141,094 20.21 %
Schedule of Composition of Net Deferred Tax Liabilities	The composition of net deferred tax liabilities is as follows: December 31, (In thousands) 2020 2019 Deferred Tax Assets Net operating losses $ 22,177 $ 22,360 Alternative minimum tax credits — 22,120 Incentive compensation 16,427 17,776 Deferred compensation 5,753 5,463 Post-retirement benefits 7,482 7,847 Equity method investments — 21,454 Capital loss carryforward 16,486 — Leases 7,709 8,192 Other 3,267 1,336 Less: valuation allowance (28,231) (31,763) Total 51,070 74,785 Deferred Tax Liabilities Properties and equipment 809,919 768,692 Equity method investments 1,649 — Leases 7,709 8,192 Derivative instruments 5,988 5 Total 825,265 776,889 Net deferred tax liabilities $ 774,195 $ 702,104
Schedule of Reconciliation of Unrecognized Tax Benefits	A reconciliation of unrecognized tax benefits is as follows: Year Ended December 31, (In thousands) 2020 2019 2018 Balance at beginning of year $ 520 $ 16,850 $ 663 Additions for tax positions of current year 499 — — Additions for tax positions of prior years 5,465 — 16,187 Reductions for tax positions of prior years — (16,330) — Balance at end of year $ 6,484 $ 520 $ 16,850

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
Employee Benefit Plans (Tables)	Dec. 31, 2020
Retirement Benefits [Abstract]
Change in Postretirement Benefit Obligation	The change in the Company's postretirement benefit obligation is as follows: Year Ended December 31, (In thousands) 2020 2019 2018 Change in Benefit Obligation Benefit obligation at beginning of year $ 34,438 $ 29,777 $ 31,050 Service cost 1,493 1,533 1,776 Interest cost 974 1,283 1,172 Actuarial (gain) loss (2,119) 3,279 (3,165) Benefits paid (2,042) (1,434) (1,056) Benefit obligation at end of year $ 32,744 $ 34,438 $ 29,777 Change in Plan Assets Fair value of plan assets at end of year — — — Funded status at end of year $ (32,744) $ (34,438) $ (29,777)
Schedule of Amounts Recognized in Balance Sheet	Amounts recognized in the balance sheet consist of the following: December 31, (In thousands) 2020 2019 2018 Current liabilities $ 2,031 $ 1,725 $ 1,865 Non-current liabilities 30,713 32,713 27,912 $ 32,744 $ 34,438 $ 29,777
Schedule of Amounts Recognized in Accumulated Other Comprehensive Income (Loss)	Amounts recognized in accumulated other comprehensive income (loss) consist of the following: December 31, (In thousands) 2020 2019 2018 Net actuarial (gain) loss $ (57) $ 2,025 $ (1,253) Prior service cost (3,078) (3,787) (4,497) $ (3,135) $ (1,762) $ (5,750) Components of Net Periodic Benefit Cost and Other Amounts Recognized in Other Comprehensive Income (Loss) Year Ended December 31, (In thousands) 2020 2019 2018 Components of Net Periodic Postretirement Benefit Cost Service cost $ 1,493 $ 1,533 $ 1,776 Interest cost 974 1,283 1,172 Amortization of prior service cost (709) (709) (709) Amortization of net loss (36) — — Net periodic postretirement cost $ 1,722 $ 2,107 $ 2,239 Other Changes in Benefit Obligations Recognized in Other Comprehensive Income (Loss) Net (gain) loss $ (2,118) $ 3,279 $ (3,165) Amortization of prior service cost 709 709 709 Amortization of net loss 36 — — Total recognized in other comprehensive income (1,373) 3,988 (2,456) Total recognized in net periodic benefit cost (income) and other comprehensive income $ 349 $ 6,095 $ (217)
Assumptions Used to Determine Projected Postretirement Benefit Obligations and Postretirement Costs	Assumptions used to determine projected postretirement benefit obligations and postretirement costs are as follows: December 31, 2020 2019 2018 Discount rate (1) 2.65 % 3.50 % 4.45 % Health care cost trend rate for medical benefits assumed for next year (pre-65) 6.75 % 7.00 % 7.25 % Health care cost trend rate for medical benefits assumed for next year (post-65) 5.00 % 5.25 % 5.50 % Ultimate trend rate (pre-65) 4.50 % 4.50 % 4.50 % Ultimate trend rate (post-65) 4.50 % 4.50 % 4.50 % Year that the rate reaches the ultimate trend rate (pre-65) 2030 2030 2030 Year that the rate reaches the ultimate trend rate (post-65) 2023 2023 2023 _______________________________________________________________________________ (1) Represents the year end rates used to determine the projected benefit obligation. To compute postretirement cost in 2020, 2019 and 2018, respectively, the beginning of year discount rates of 3.50 percent, 4.45 percent and 3.85 percent were used.
Schedule of Estimated Benefit Payments	The following estimated benefit payments under the Company's postretirement plans, which reflect expected future service, are expected to be paid as follows: (In thousands) 2021 $ 2,058 2022 2,085 2023 1,984 2024 1,860 2025 1,789 Years 2026 - 2030 9,018

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
Stock-Based Compensation (Tables)	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Summary of Restricted Stock Award / Unit Activity	The following table is a summary of restricted stock award activity: Year Ended December 31, 2020 2019 2018 Shares Weighted- Shares Weighted- Shares Weighted- Outstanding at beginning of period 58,834 $ 25.19 150,293 $ 28.12 161,450 $ 28.00 Granted — — 55,500 25.29 — — Vested (6,334) 24.39 (143,959) 28.29 (7,157) 25.17 Forfeited (2,000) 25.29 (3,000) 25.29 (4,000) 28.45 Outstanding at end of period (1)(2) 50,500 $ 25.29 58,834 $ 25.19 150,293 $ 28.12 __________________________________________________________________ (1) As of December 31, 2020, the aggregate intrinsic value was $0.8 million and was calculated by multiplying the closing market price of the Company's stock on December 31, 2020 by the number of non-vested restricted stock awards outstanding. (2) As of December 31, 2020, the weighted average remaining contractual term of non-vested restricted stock awards outstanding was 1.4 years. The following table is a summary of restricted stock unit activity: Year Ended December 31, 2020 2019 2018 Shares Weighted- Shares Weighted- Shares Weighted- Outstanding at beginning of period 574,219 $ 18.47 490,415 $ 17.41 407,563 $ 16.17 Granted and fully vested 130,065 15.88 83,804 24.70 82,852 23.47 Issued — — — — — — Forfeited — — — — — — Outstanding at end of period (1)(2) 704,284 $ 17.99 574,219 $ 18.47 490,415 $ 17.41 _______________________________________________________________________________ (1) As of December 31, 2020, the aggregate intrinsic value was $11.5 million and was calculated by multiplying the closing market price of the Company's stock on December 31, 2020 by the number of outstanding restricted stock units. (2) Due to the immediate vesting of the units and the unknown term of each director, the weighted-average remaining contractual term in years has not been provided.
Schedule of Performance Share Awards Activity	The following table is a summary of activity for Employee Performance Share Awards: Year Ended December 31, 2020 2019 2018 Shares Weighted- Shares Weighted- Shares Weighted- Outstanding at beginning of period 1,259,287 $ 23.64 1,280,021 $ 22.22 1,095,970 $ 23.31 Granted 722,500 15.60 526,730 24.95 531,670 23.25 Issued and fully vested (334,640) 22.60 (388,370) 20.49 (315,970) 27.71 Forfeited (37,023) 20.38 (159,094) 24.29 (31,649) 22.33 Outstanding at end of period 1,610,124 $ 20.31 1,259,287 $ 23.64 1,280,021 $ 22.22 The following table is a summary of activity for the Hybrid Performance Share Awards: Year Ended December 31, 2020 2019 2018 Shares Weighted- Shares Weighted- Shares Weighted- Outstanding at beginning of period 692,788 $ 23.90 662,388 $ 22.48 574,354 $ 22.72 Granted 506,412 15.60 315,029 24.95 321,720 23.25 Issued and fully vested (295,649) 23.40 (284,629) 21.78 (233,686) 24.12 Forfeited — — — — — — Outstanding at end of period 903,551 $ 19.41 692,788 $ 23.90 662,388 $ 22.48 The following table is a summary of activity for the TSR Performance Share Awards: Year Ended December 31, 2020 2019 2018 Shares Weighted- Average Grant Date Fair Value per Share (1) Shares Weighted- Average Grant Date Fair Value per Share (1) Shares Weighted- Average Grant Date Fair Value per Share (1) Outstanding at beginning of period 1,428,634 $ 20.17 1,299,868 $ 19.47 1,109,708 $ 19.23 Granted 862,180 13.79 536,673 20.63 482,581 19.92 Issued and fully vested (891,961) 19.89 (407,907) 18.57 (292,421) 19.29 Forfeited — — — — — — Outstanding at end of period 1,398,853 $ 16.41 1,428,634 $ 20.17 1,299,868 $ 19.47 _______________________________________________________________________________ (1) The grant date fair value figures in this table represent the fair value of the equity component of the performance share awards.
Assumptions Used to Determine Grant Date Fair Value of Equity and Liability Component	The following assumptions were used to determine the grant date fair value of the equity component of the TSR Performance Share Awards for the respective periods: Year Ended December 31, 2020 2019 2018 Fair value per performance share award granted during the period $ 13.79 $ 20.63 $ 19.92 Assumptions Stock price volatility 29.5 % 31.3 % 37.3 % Risk free rate of return 1.4 % 2.5 % 2.4 % The following assumptions were used to determine the fair value of the liability component of the TSR Performance Share Awards for the respective periods: December 31, 2020 2019 2018 Fair value per performance share award at the end of the period $10.37 - $10.81 $6.18 - $14.80 $15.15 - $20.12 Assumptions Stock price volatility 42.4% - 52.4% 29.8% - 30.4% 29.9% - 31.1% Risk free rate of return 0.1% 1.6% 2.5% - 2.6%

Earnings per Common Share (Tabl

Earnings per Common Share (Tables)	12 Months Ended
Earnings per Common Share (Tables)	Dec. 31, 2020
Earnings Per Share [Abstract]
Calculation of Basic and Diluted Weighted-Average Shares Outstanding	The following is a calculation of basic and diluted weighted-average shares outstanding: Year Ended December 31, (In thousands) 2020 2019 2018 Weighted-average shares - basic 398,521 415,514 445,538 Dilution effect of stock awards at end of period 2,001 1,937 2,030 Weighted-average shares - diluted 400,522 417,451 447,568
Calculation of Weighted-Average Shares Excluded from Diluted EPS Due to Anti-Dilutive Effect	The following is a calculation of weighted-average shares excluded from diluted EPS due to the anti-dilutive effect: Year Ended December 31, (In thousands) 2020 2019 2018 Weighted-average stock awards excluded from diluted EPS due to the anti-dilutive effect calculated using the treasury stock method 2 669 3

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Tables)	12 Months Ended
Accumulated Other Comprehensive Income (Tables)	Dec. 31, 2020
Equity [Abstract]
Changes in Accumulated Other Comprehensive Income by Component, Net of Tax	Changes in accumulated other comprehensive income by component, net of tax, were as follows: (In thousands) Postretirement Balance at December 31, 2017 $ 2,077 Other comprehensive income before reclassifications 2,461 Amounts reclassified from accumulated other comprehensive loss (101) Net current-period other comprehensive income 2,360 Balance at December 31, 2018 $ 4,437 Other comprehensive income before reclassifications (2,530) Amounts reclassified from accumulated other comprehensive loss (547) Net current-period other comprehensive income (3,077) Balance at December 31, 2019 $ 1,360 Other comprehensive income before reclassifications 1,634 Amounts reclassified from accumulated other comprehensive loss (575) Net current-period other comprehensive income 1,059 Balance at December 31, 2020 $ 2,419
Schedule of Amounts Reclassified from Accumulated Other Comprehensive Income into Consolidated Statement of Operations	Amounts reclassified from accumulated other comprehensive income into the Consolidated Statement of Operations were as follows: Year Ended December 31, Affected Line Item in the (In thousands) 2020 2019 2018 Postretirement benefits Amortization of prior service cost $ 709 $ 709 $ 709 General and administrative expense Amortization of net (gain) loss 36 — — General and administrative expense Total before tax 745 709 709 Income before income taxes Income tax expense (170) (162) (162) Income tax expense Cumulative effect of adoption of ASU 2018-02 reclassified to retained earnings — — (446) Retained earnings Total reclassifications for the period $ 575 $ 547 $ 101 Net income

Additional Balance Sheet Info_2

Additional Balance Sheet Information (Tables)	12 Months Ended
Additional Balance Sheet Information (Tables)	Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Certain Balance Sheet Amounts	Certain balance sheet amounts are comprised of the following: December 31, (In thousands) 2020 2019 Accounts receivable, net Trade accounts $ 215,301 $ 209,200 Other accounts 462 1,007 215,763 210,207 Allowance for doubtful accounts (1,039) (1,184) $ 214,724 $ 209,023 Other assets Deferred compensation plan $ 22,510 $ 18,381 Debt issuance cost 6,875 8,938 Operating lease right-of-use assets 33,741 35,916 Other accounts 85 56 $ 63,211 $ 63,291 Accounts payable Trade accounts $ 12,896 $ 21,663 Royalty and other owners 37,243 36,191 Accrued transportation 52,238 55,586 Accrued capital costs 37,872 40,337 Taxes other than income 13,736 16,971 Other accounts 8,096 19,063 $ 162,081 $ 189,811 Accrued liabilities Employee benefits $ 14,270 $ 22,727 Taxes other than income 3,026 3,850 Operating lease liabilities 3,991 3,124 Other accounts 1,087 1,589 $ 22,374 $ 31,290 Other liabilities Deferred compensation plan $ 30,581 $ 27,012 Operating lease liabilities 29,628 32,677 Other accounts 21,069 8,595 $ 81,278 $ 68,284

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	12 Months Ended
Supplemental Cash Flow Information (Tables)	Dec. 31, 2020
Supplemental Cash Flow Elements [Abstract]
Summary of Cash Paid for Interest and Income Taxes	Year Ended December 31, (In thousands) 2020 2019 2018 Cash paid for interest and income taxes Interest $ 57,043 $ 57,475 $ 80,069 Income taxes 10,964 7,808 4,635
Summary of Cash Equivalents and Restricted Cash	Cash, cash equivalents and restricted cash, included in the Consolidated Statement of Cash Flow, is comprised of the following: December 31, (In thousands) 2020 2019 Cash and cash equivalents $ 140,113 $ 200,227 Restricted cash 11,578 13,556 $ 151,691 $ 213,783
Schedule of Cash and Cash Equivalents	Cash, cash equivalents and restricted cash, included in the Consolidated Statement of Cash Flow, is comprised of the following: December 31, (In thousands) 2020 2019 Cash and cash equivalents $ 140,113 $ 200,227 Restricted cash 11,578 13,556 $ 151,691 $ 213,783

SUPPLEMENTAL OIL AND GAS INFO_2

SUPPLEMENTAL OIL AND GAS INFORMATION (UNAUDITED) (Tables)	12 Months Ended
SUPPLEMENTAL OIL AND GAS INFORMATION (UNAUDITED) (Tables)	Dec. 31, 2020
Extractive Industries [Abstract]
Schedule of Proved Developed and Undeveloped Oil and Gas Reserve Quantities	The following tables illustrate the Company's net proved reserves, including changes, and proved developed and proved undeveloped reserves for the periods indicated, as estimated by the Company's engineering staff. All reserves are located within the continental United States. Natural Gas Crude Oil & NGLs (Mbbl) (1) Total (Bcfe) (2) December 31, 2017 9,353 62,252 9,726 Revision of prior estimates (3) 776 677 780 Extensions, discoveries and other additions (4) 2,243 — 2,244 Production (730) (829) (735) Sales of reserves in place (5) (38) (61,980) (410) December 31, 2018 11,604 120 11,605 Revision of prior estimates (6) 48 (48) 47 Extensions, discoveries and other additions (4) 2,116 — 2,116 Production (865) — (865) Sales of reserves in place — (50) — December 31, 2019 12,903 22 12,903 Revision of prior estimates (7) (347) (3) (347) Extensions, discoveries and other additions (4) 1,974 — 1,974 Production (858) (4) (858) December 31, 2020 13,672 15 13,672 Proved Developed Reserves December 31, 2017 6,001 31,066 6,187 December 31, 2018 7,402 107 7,403 December 31, 2019 8,056 22 8,056 December 31, 2020 8,608 15 8,608 Proved Undeveloped Reserves December 31, 2017 3,352 31,186 3,539 December 31, 2018 4,202 13 4,202 December 31, 2019 4,847 — 4,847 December 31, 2020 5,064 — 5,064 _______________________________________________________________________________ (1) There were no significant NGL reserves for 2020, 2019 and 2018. For 2017, NGL reserves were less than one percent of the Company's total proved equivalent reserves and 13.7 percent of the Company's proved crude oil and NGL reserves. (2) Includes natural gas and natural gas equivalents determined by using the ratio of 6 Mcf of natural gas to 1 Bbl of crude oil, condensate or NGLs. (3) The net upward revision of 780 Bcfe was primarily due to an upward revision of 1,123 Bcfe associated with positive drilling results in the Dimock field in northeast Pennsylvania, partially offset by a downward revision of 345 Bcfe associated with proved undeveloped (PUD) reserves reclassifications. (4) Extensions, discoveries and other additions were primarily related to drilling activity in the Dimock field located in northeast Pennsylvania. The Company added 1,974 Bcfe, 2,116 Bcfe and 2,243 Bcfe of proved reserves in this field in 2020, 2019 and 2018, respectively. (5) Sales of reserves in place were primarily related to the divestiture of certain oil and gas properties in the Eagle Ford Shale in February 2018 and the Haynesville Shale in July 2018, which represented 404 Bcfe and 6 Bcfe, respectively. (6) The net upward revision of 47 Bcfe was primarily due to a net upward performance revision of 67 Bcfe, partially offset by a downward revision of 18 Bcfe associated with PUD reclassifications as a result of the five-year limitation. The net upward performance revision of 67 Bcfe was primarily due to an upward revision of 417 Bcfe associated with the Company's PUD reserves due to performance revisions and the drilling of longer lateral length wells, partially offset by a downward performance revision of 350 Bcfe related to certain proved developed producing properties. (7) The net downward revision of 347 Bcfe was primarily due to a net downward performance revision of 245 Bcfe and a downward revision of 66 Bcfe associated with PUD reclassifications as a result of the five-year limitation. The net downward performance revision of 245 Bcfe was primarily due to a downward performance revision of 368 Bcfe related to certain proved developed producing properties, partially offset by an upward revision of 123 Bcfe associated with our PUD reserves due to performance revisions and the drilling of longer lateral length wells.
Capitalized Costs Relating to Oil and Gas Producing Activities Disclosure	Capitalized costs relating to oil and gas producing activities and related accumulated depreciation, depletion and amortization were as follows: December 31, (In thousands) 2020 2019 2018 Aggregate capitalized costs relating to oil and gas producing activities $ 7,154,452 $ 6,676,122 $ 5,995,194 Aggregate accumulated depreciation, depletion and amortization (3,148,564) (2,861,014) (2,540,068) Net capitalized costs $ 4,005,888 $ 3,815,108 $ 3,455,126
Cost Incurred in Oil and Gas Property Acquisition, Exploration, and Development Activities Disclosure	Costs incurred in property acquisition, exploration and development activities were as follows: Year Ended December 31, (In thousands) 2020 2019 2018 Property acquisition costs, proved $ — $ — $ — Property acquisition costs, unproved 5,821 6,072 29,851 Exploration costs 15,419 20,270 94,309 Development costs 546,646 761,326 778,574 Total costs $ 567,886 $ 787,668 $ 902,734
Oil and Gas, Average Sale Price and Production Cost	The average prices (adjusted for basis and quality differentials) related to proved reserves are as follows: Year Ended December 31, 2020 2019 2018 Natural gas $ 1.64 $ 2.35 $ 2.58 Crude oil $ 32.53 $ 55.80 $ 65.21 NGLs $ — $ — $ 21.64
Standardized Measure of Discounted Future Cash Flows Relating to Proved Reserves Disclosure	Standardized Measure is as follows: Year Ended December 31, (In thousands) 2020 2019 2018 Future cash inflows $ 22,385,385 $ 30,302,480 $ 29,904,474 Future production costs (10,783,895) (10,039,294) (8,702,734) Future development costs (1) (1,612,659) (2,006,167) (1,766,796) Future income tax expenses (2,175,916) (4,042,787) (4,166,089) Future net cash flows 7,812,915 14,214,232 15,268,855 10% annual discount for estimated timing of cash flows (4,750,760) (8,353,115) (8,785,547) Standardized measure of discounted future net cash flows $ 3,062,155 $ 5,861,117 $ 6,483,308 ______________________________________________________________________________
Schedule of Changes in Standardized Measure of Discounted Future Net Cash Flows	The following is an analysis of the changes in the Standardized Measure: Year Ended December 31, (In thousands) 2020 2019 2018 Beginning of year $ 5,861,117 $ 6,483,308 $ 5,010,446 Discoveries and extensions, net of related future costs 311,336 1,075,839 1,280,499 Net changes in prices and production costs (4,326,254) (1,510,104) 2,078,479 Accretion of discount 750,041 813,480 596,569 Revisions of previous quantity estimates (107,467) 28,310 586,494 Timing and other 5,992 (192,563) (76,761) Development costs incurred 501,093 468,748 338,297 Sales and transfers, net of production costs (746,310) (1,316,752) (1,343,872) Sales of reserves in place — (1,350) (1,290,594) Net change in income taxes 812,607 12,201 (696,249) End of year $ 3,062,155 $ 5,861,117 $ 6,483,308

QUARTERLY FINANCIAL INFORMATI_2

QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Tables)	12 Months Ended
QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Tables)	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (In thousands, except per share amounts) First Second Third Fourth Total 2020 Operating revenues $ 386,457 $ 332,348 $ 291,041 $ 456,778 $ 1,466,624 Operating income (loss) 86,401 53,716 (7,533) 162,892 295,476 Net income (loss) 53,910 30,374 (14,961) 131,206 200,529 Basic earnings (loss) per share 0.14 0.08 (0.04) 0.33 0.50 Diluted earnings (loss) per share 0.13 0.08 (0.04) 0.33 0.50 2019 Operating revenues $ 641,681 $ 534,117 $ 429,111 $ 461,368 $ 2,066,277 Earnings on equity method investments (1) 3,684 3,650 3,860 69,302 80,496 Operating income 352,959 250,805 129,777 222,209 955,750 Net income 262,763 181,009 90,358 146,940 681,070 Basic earnings per share 0.62 0.43 0.22 0.36 1.64 Diluted earnings per share 0.62 0.43 0.22 0.36 1.63 _______________________________________________________________________________ (1) Earnings on equity method investments in the fourth quarter of 2019 includes a gain on sale of $75.8 million associated with the Company's sale of its equity investment in Meade.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Narrative (Details)	12 Months Ended
	Dec. 31, 2020USD ($)InstitutionSegment	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Properties and Equipment
Number of operating segments \| Segment	1
Number of financial institutions \| Institution	1
Restricted cash	$ 11,578,000	$ 13,556,000
Amortization of unproved properties included in depreciation, depletion and amortization	8,200,000	32,600,000	$ 82,300,000
Assets legally restricted for purposes of settling asset retirement obligations	0	0
Finance leases	0	0
Accounts Payable
Properties and Equipment
Book overdraft	$ 0	$ 0
Buildings \| Minimum
Properties and Equipment
Estimated useful life	25 years
Buildings \| Maximum
Properties and Equipment
Estimated useful life	40 years
Other Assets \| Minimum
Properties and Equipment
Estimated useful life	3 years
Other Assets \| Maximum
Properties and Equipment
Estimated useful life	25 years
Customer One \| Sales Revenue, Net \| Customer
Concentration Risk [Line Items]
Percentage of Total Sales	21.00%	17.00%	20.00%
Customer Two \| Sales Revenue, Net \| Customer
Concentration Risk [Line Items]
Percentage of Total Sales	16.00%	16.00%	11.00%
Customer Three \| Sales Revenue, Net \| Customer
Concentration Risk [Line Items]
Percentage of Total Sales	12.00%

Divestitures - Narrative (Detai

Divestitures - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended	12 Months Ended
Divestitures - Narrative (Details) - USD ($) $ in Thousands	Jul. 31, 2018	Feb. 28, 2018	Dec. 31, 2017	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Significant Acquisitions and Disposals
Gain (loss) on sale of assets				$ (491)	$ (1,462)	$ (16,327)
Proceeds from sale of assets				$ 828	$ 2,600	$ 678,350
Oil and Gas Properties, Proved and Unproved \| Haynesville Shale
Significant Acquisitions and Disposals
Gain (loss) on sale of assets			$ 29,700
Proceeds from sale of assets	$ 30,000		5,000
Oil and Gas Properties, Proved and Unproved \| Eagle Ford Shale
Significant Acquisitions and Disposals
Gain (loss) on sale of assets			(45,400)
Proceeds from sale of assets		$ 765,000	76,500
Impairment of oil and gas properties			$ 414,300

Properties and Equipment, Net -

Properties and Equipment, Net - Components of Properties and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Proved oil and gas properties	$ 7,068,605	$ 6,508,443
Unproved oil and gas properties	49,829	133,475
Land, buildings and other equipment	92,566	104,700
Properties and equipment, gross, total	7,211,000	6,746,618
Accumulated depreciation, depletion and amortization	(3,166,394)	(2,890,912)
Properties and equipment, net	$ 4,044,606	$ 3,855,706

Properties and Equipment, Net_2

Properties and Equipment, Net - Schedule of Net Changes in Capitalized Exploratory Well Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net changes in capitalized exploratory well costs
Balance at beginning of period	$ 0	$ 0	$ 19,511
Additions to capitalized exploratory well costs pending the determination of proved reserves	0	0	0
Reclassifications to wells, facilities, and equipment based on the determination of proved reserves	0	0	0
Capitalized exploratory well costs charged to expense	0	0	(19,511)
Balance at end of period	$ 0	$ 0	$ 0

Properties and Equipment, Net_3

Properties and Equipment, Net - Schedule of Aging of Capitalized Exploratory Well Costs (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Capitalized exploratory well costs that have been capitalized for a period of one year or less	$ 0	$ 0	$ 0
Capitalized exploratory well costs that have been capitalized for a period greater than one year	0	0	0
Capitalized exploratory well costs	$ 0	$ 0	$ 0	$ 19,511

Equity Method Investments - Act

Equity Method Investments - Activity Related to Equity Method Investments (Details) - USD ($) $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Equity Method Investments
Balance at beginning of period				$ 163,181	$ 0	$ 163,181	$ 86,077
Contributions					35	9,338	77,263
Distributions					0	(17,453)	(1,296)
(Loss) earnings on equity method investments	$ 69,302	$ 3,860	$ 3,650	3,684	(59)	80,496	1,137
Reclassification of accumulated losses					0	9,400	0
Sale of investment					24	(244,962)	0
Balance at end of period	0				0	0	163,181
Constitution
Equity Method Investments
Balance at beginning of period				0	0	0	732
Contributions					35	725	500
Distributions					0	0	0
(Loss) earnings on equity method investments					(35)	(10,125)	(1,232)
Reclassification of accumulated losses					0	9,400	0
Sale of investment					0	0	0
Balance at end of period	0				0	0	0
Meade
Equity Method Investments
Balance at beginning of period				$ 163,181	0	163,181	85,345
Contributions					0	8,613	76,763
Distributions					0	(17,453)	(1,296)
(Loss) earnings on equity method investments					(24)	90,621	2,369
Reclassification of accumulated losses					0	0	0
Sale of investment					24	(244,962)	0
Balance at end of period	$ 0				$ 0	$ 0	$ 163,181

Equity Method Investments - Nar

Equity Method Investments - Narrative (Details) - USD ($) $ in Thousands	Feb. 10, 2020	Nov. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Feb. 28, 2014	Apr. 30, 2012
Schedule of Equity Method Investments [Line Items]
Well costs			$ 0	$ 0	$ 0	$ 19,511
Payments for sale of equity method investments			9,424
Net proceeds from sale of investment				249,463	$ 0
Restricted cash			$ 11,578	13,556
Transcontinental Gas Pipe Line Company LLC
Schedule of Equity Method Investments [Line Items]
Entity's equity interest in construction agreement (as a percent)							61.00%
Meade Pipeline Co LLC
Schedule of Equity Method Investments [Line Items]
Entity's equity interest in construction agreement (as a percent)							39.00%
Constitution Pipeline Company, LLC
Schedule of Equity Method Investments [Line Items]
Ownership interest	25.00%							25.00%
Payable for disposal of equity method investment				$ 9,400
Payments for sale of equity method investments	$ 9,400
Meade Pipeline Co LLC
Schedule of Equity Method Investments [Line Items]
Ownership interest							20.00%
Net proceeds from sale of investment		$ 249,500
Gain on sale of investment		$ 75,800

Debt and Credit Agreements - Sc

Debt and Credit Agreements - Schedule of Long-term Debt and Credit Agreements (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ (3,076)	$ (3,975)
Long-term debt	1,133,924	1,220,025
Current portion of long-term debt	$ 188,000	87,000
6.51% weighted-average senior notes
Debt Instrument [Line Items]
Weighted-average interest rate	6.51%
Long-term debt including unamortized debt issuance costs	$ 37,000	124,000
Current portion of long-term debt		87,000
5.58% weighted-average senior notes
Debt Instrument [Line Items]
Weighted-average interest rate	5.58%
Long-term debt including unamortized debt issuance costs	$ 175,000	175,000
Current portion of long-term debt	$ 88,000
3.65% weighted-average senior notes
Debt Instrument [Line Items]
Weighted-average interest rate	3.65%
Long-term debt including unamortized debt issuance costs	$ 925,000	925,000
Current portion of long-term debt	100,000
Revolving credit facility
Debt Instrument [Line Items]
Long-term debt including unamortized debt issuance costs	$ 0	$ 0

Debt and Credit Agreements - Na

Debt and Credit Agreements - Narrative (Details)	Apr. 22, 2019USD ($)	Jan. 31, 2021USD ($)	May 31, 2016USD ($)	Sep. 30, 2014USD ($)TrancheInvestor	Dec. 31, 2010USD ($)InvestorTranche	Jul. 31, 2008USD ($)TrancheInvestor	Dec. 31, 2020USD ($)fiscal_period	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Debt Instrument [Line Items]
Debt maturities, due in 2021							$ 188,000,000
Debt maturities, due in 2023							62,000,000
Debt maturities, due in 2024							575,000,000
Repayments of debt							283,000,000	$ 102,000,000	$ 455,000,000
Deferred financing costs capitalized							$ 3,076,000	3,975,000
Unamortized discount								3,400,000
6.51% Weighted-average Senior Notes
Debt Instrument [Line Items]
Weighted-average interest rate							6.51%
Long-term debt							$ 37,000,000	124,000,000
5.58% Weighted-average Senior Notes
Debt Instrument [Line Items]
Weighted-average interest rate							5.58%
Long-term debt							$ 175,000,000	175,000,000
3.65% Weighted-average Senior Notes
Debt Instrument [Line Items]
Weighted-average interest rate							3.65%
Long-term debt							$ 925,000,000	925,000,000
Revolving Credit Facility
Debt Instrument [Line Items]
Minimum required asset coverage ratio							1.75
Fiscal quarters for reduction in coverage ratio \| fiscal_period							4
Minimum required annual coverage ratio							2.8
Maximum borrowing capacity on line of credit	$ 3,200,000,000
Remaining borrowing capacity on line of credit	$ 1,500,000,000						$ 1,500,000,000
Minimum current ratio							1
Long-term debt							$ 0	$ 0
Interest rate							4.00%	6.30%
Subsequent Event \| 6.51% Weighted-average Senior Notes
Debt Instrument [Line Items]
Amount of principal repurchased		$ 88,000,000
Weighted-average interest rate		5.58%
Senior Notes
Debt Instrument [Line Items]
Minimum required asset coverage ratio							1.75
Fiscal quarters for reduction in coverage ratio \| fiscal_period							4
Minimum required annual coverage ratio							2.8
Senior Notes \| 6.51% Weighted-average Senior Notes
Debt Instrument [Line Items]
Principal						$ 425,000,000
Number of institutional investors \| Investor						41
Number of debt tranches \| Tranche						3
Repayments of debt							$ 388,000,000
Senior Notes \| 5.58% Weighted-average Senior Notes
Debt Instrument [Line Items]
Principal					$ 175,000,000
Number of institutional investors \| Investor					8
Number of debt tranches \| Tranche					3
Senior Notes \| 3.65% Weighted-average Senior Notes
Debt Instrument [Line Items]
Principal				$ 925,000,000
Number of institutional investors \| Investor				24
Number of debt tranches \| Tranche				3
Revolving Credit Facility
Debt Instrument [Line Items]
Long-term debt							$ 0
Deferred financing costs capitalized								$ 7,400,000
Senior Notes \| 6.51% Weighted-average Senior Notes
Debt Instrument [Line Items]
Amount of principal repurchased			$ 64,000,000
Repayments of debt			68,300,000
Tranche 1 \| Senior Notes \| 6.51% Weighted-average Senior Notes
Debt Instrument [Line Items]
Principal						$ 245,000,000
Tranche 1 \| Senior Notes \| 5.58% Weighted-average Senior Notes
Debt Instrument [Line Items]
Principal					$ 88,000,000
Tranche 1 \| Senior Notes \| 3.65% Weighted-average Senior Notes
Debt Instrument [Line Items]
Principal				$ 100,000,000
Tranche 1 \| Senior Notes \| 6.51% Weighted-average Senior Notes
Debt Instrument [Line Items]
Amount of principal repurchased			8,000,000
Tranche 2 \| Senior Notes \| 6.51% Weighted-average Senior Notes
Debt Instrument [Line Items]
Principal						100,000,000
Tranche 2 \| Senior Notes \| 5.58% Weighted-average Senior Notes
Debt Instrument [Line Items]
Principal					25,000,000
Tranche 2 \| Senior Notes \| 3.65% Weighted-average Senior Notes
Debt Instrument [Line Items]
Principal				575,000,000
Tranche 2 \| Senior Notes \| 6.51% Weighted-average Senior Notes
Debt Instrument [Line Items]
Amount of principal repurchased			13,000,000
Tranche 3 \| Senior Notes \| 6.51% Weighted-average Senior Notes
Debt Instrument [Line Items]
Principal						$ 80,000,000
Tranche 3 \| Senior Notes \| 5.58% Weighted-average Senior Notes
Debt Instrument [Line Items]
Principal					$ 62,000,000
Tranche 3 \| Senior Notes \| 3.65% Weighted-average Senior Notes
Debt Instrument [Line Items]
Principal				$ 250,000,000
Tranche 3 \| Senior Notes \| 6.51% Weighted-average Senior Notes
Debt Instrument [Line Items]
Amount of principal repurchased			$ 43,000,000
External Credit Rating, Non Investment Grade \| Minimum \| Revolving Credit Facility
Debt Instrument [Line Items]
Commitment fee percentage	30.00%
External Credit Rating, Non Investment Grade \| Minimum \| Revolving Credit Facility \| ABR Loans
Debt Instrument [Line Items]
Basis spread on variable rate	50.00%
External Credit Rating, Non Investment Grade \| Minimum \| Revolving Credit Facility \| LIBOR Loans
Debt Instrument [Line Items]
Basis spread on variable rate	150.00%
External Credit Rating, Non Investment Grade \| Maximum \| Revolving Credit Facility
Debt Instrument [Line Items]
Commitment fee percentage	42.50%
External Credit Rating, Non Investment Grade \| Maximum \| Revolving Credit Facility \| ABR Loans
Debt Instrument [Line Items]
Basis spread on variable rate	125.00%
External Credit Rating, Non Investment Grade \| Maximum \| Revolving Credit Facility \| LIBOR Loans
Debt Instrument [Line Items]
Basis spread on variable rate	225.00%
External Credit Rating, Investment Grade \| Minimum \| Revolving Credit Facility
Debt Instrument [Line Items]
Commitment fee percentage	12.50%
External Credit Rating, Investment Grade \| Minimum \| Revolving Credit Facility \| ABR Loans
Debt Instrument [Line Items]
Basis spread on variable rate	12.50%
External Credit Rating, Investment Grade \| Minimum \| Revolving Credit Facility \| LIBOR Loans
Debt Instrument [Line Items]
Basis spread on variable rate	112.50%
External Credit Rating, Investment Grade \| Maximum \| Revolving Credit Facility
Debt Instrument [Line Items]
Commitment fee percentage	27.50%
External Credit Rating, Investment Grade \| Maximum \| Revolving Credit Facility \| ABR Loans
Debt Instrument [Line Items]
Basis spread on variable rate	75.00%
External Credit Rating, Investment Grade \| Maximum \| Revolving Credit Facility \| LIBOR Loans
Debt Instrument [Line Items]
Basis spread on variable rate	175.00%

Debt and Credit Agreements - _2

Debt and Credit Agreements - Schedule of Senior Unsecured Notes Issued (Details) - Senior Notes - USD ($)	1 Months Ended
	Sep. 30, 2014	Dec. 31, 2010	Jul. 31, 2008
6.51% weighted-average senior notes
Debt Instrument [Line Items]
Principal			$ 425,000,000
6.51% weighted-average senior notes \| Tranche 1
Debt Instrument [Line Items]
Principal			$ 245,000,000
Term			10 years
Coupon			6.44%
6.51% weighted-average senior notes \| Tranche 2
Debt Instrument [Line Items]
Principal			$ 100,000,000
Term			12 years
Coupon			6.54%
6.51% weighted-average senior notes \| Tranche 3
Debt Instrument [Line Items]
Principal			$ 80,000,000
Term			15 years
Coupon			6.69%
5.58% weighted-average senior notes
Debt Instrument [Line Items]
Principal		$ 175,000,000
5.58% weighted-average senior notes \| Tranche 1
Debt Instrument [Line Items]
Principal		$ 88,000,000
Term		10 years
Coupon		5.42%
5.58% weighted-average senior notes \| Tranche 2
Debt Instrument [Line Items]
Principal		$ 25,000,000
Term		12 years
Coupon		5.59%
5.58% weighted-average senior notes \| Tranche 3
Debt Instrument [Line Items]
Principal		$ 62,000,000
Term		15 years
Coupon		5.80%
3.65% weighted-average senior notes
Debt Instrument [Line Items]
Principal	$ 925,000,000
3.65% weighted-average senior notes \| Tranche 1
Debt Instrument [Line Items]
Principal	$ 100,000,000
Term	7 years
Coupon	3.24%
3.65% weighted-average senior notes \| Tranche 2
Debt Instrument [Line Items]
Principal	$ 575,000,000
Term	10 years
Coupon	3.67%
3.65% weighted-average senior notes \| Tranche 3
Debt Instrument [Line Items]
Principal	$ 250,000,000
Term	12 years
Coupon	3.77%

Derivative Instruments - Summar

Derivative Instruments - Summary of Outstanding Financial Commodity Derivatives (Details) - Natural gas (NYMEX)	1 Months Ended	12 Months Ended
	Feb. 26, 2021MMBTU$ / MMBTU	Dec. 31, 2020MMBTU$ / MMBTU
Derivative [Line Items]
Volume (Mmbtu) \| MMBTU		18,250,000
Swaps, Weighted Average Price (in dollars per Mmbtu)		2.74
Volume (Mmbtu) \| MMBTU		164,250,000
Collars, Weighted-Average Floor Price (in dollars per Mmbtu)		2.68
Collars, Weighted- Average Ceiling Price (in dollars per Mmbtu)		3.09
Volume (Mmbtu) \| MMBTU		10,700,000
Collars, Floor Price (in dollars per Mmbtu)		0
Collars, Weighted-Average Floor Price (in dollars per Mmbtu)		2.50
Collars, Ceiling Price (in dollars per Mmbtu)		0
Collars, Weighted- Average Ceiling Price (in dollars per Mmbtu)		2.80
Volume (Mmbtu) \| MMBTU		10,700,000
Swaps, Weighted Average Price (in dollars per Mmbtu)		2.75
Subsequent Event
Derivative [Line Items]
Volume (Mmbtu) \| MMBTU	10,700,000
Swaps, Weighted Average Price (in dollars per Mmbtu)	2.81
Minimum
Derivative [Line Items]
Collars, Floor Price (in dollars per Mmbtu)		2.50
Minimum
Derivative [Line Items]
Collars, Ceiling Price (in dollars per Mmbtu)		2.83
Maximum
Derivative [Line Items]
Collars, Floor Price (in dollars per Mmbtu)		2.85
Maximum
Derivative [Line Items]
Collars, Ceiling Price (in dollars per Mmbtu)		3.94

Derivative Instruments - Effect

Derivative Instruments - Effect of Derivative Instruments on Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Effect of derivative instruments on the Consolidated Balance Sheet
Derivative instruments	$ 26,209	$ 31
Derivative instruments	0	9
Derivatives Not Designated as Hedges \| Commodity Contract \| Derivative instruments (current)
Effect of derivative instruments on the Consolidated Balance Sheet
Derivative instruments	26,209	31
Derivatives Not Designated as Hedges \| Commodity Contract \| Accrued liabilities
Effect of derivative instruments on the Consolidated Balance Sheet
Derivative instruments	$ 0	$ 9

Derivative Instruments - Schedu

Derivative Instruments - Schedule of Offsetting Derivative Assets and Liabilities in Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Derivative assets
Derivative instruments	$ 26,354	$ 47
Gross amounts offset in the consolidated balance sheet	(145)	(16)
Net amounts of assets presented in the consolidated balance sheet	26,209	31
Gross amounts of financial instruments not offset in the consolidated balance sheet	0	0
Net amount	26,209	31
Derivative liabilities
Gross amounts of recognized liabilities	145	25
Gross amounts offset in the consolidated balance sheet	(145)	(16)
Net amounts of liabilities presented in the consolidated balance sheet	0	9
Gross amounts of financial instruments not offset in the consolidated balance sheet	0	0
Net amount	$ 0	$ 9

Derivative Instruments - Effe_2

Derivative Instruments - Effect of Derivative Instruments on Consolidated Statement of Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Cash received (paid) on settlement of derivative instruments	$ 35,218	$ 138,450	$ (41,631)
Non-cash gain (loss) on derivative instruments	26,186	(57,642)	86,063
Total	$ 61,404	$ 80,808	$ 44,432

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Assets
Deferred compensation plan	$ 22,510	$ 18,381
Derivative instruments	26,209	31
Liabilities
Deferred compensation plan	30,581	27,012
Derivative instruments	0	9
Recurring Basis
Assets
Deferred compensation plan	22,510	18,381
Derivative instruments	26,354	47
Total assets	48,864	18,428
Liabilities
Deferred compensation plan	30,581	27,012
Derivative instruments	145	25
Total liabilities	30,726	27,037
Recurring Basis \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Deferred compensation plan	22,510	18,381
Derivative instruments	0	0
Total assets	22,510	18,381
Liabilities
Deferred compensation plan	30,581	27,012
Derivative instruments	0	0
Total liabilities	30,581	27,012
Recurring Basis \| Significant Other Observable Inputs (Level 2)
Assets
Deferred compensation plan	0	0
Derivative instruments	2,647	44
Total assets	2,647	44
Liabilities
Deferred compensation plan	0	0
Derivative instruments	0	0
Total liabilities	0	0
Recurring Basis \| Significant Unobservable Inputs (Level 3)
Assets
Deferred compensation plan	0	0
Derivative instruments	23,707	3
Total assets	23,707	3
Liabilities
Deferred compensation plan	0	0
Derivative instruments	145	25
Total liabilities	$ 145	$ 25

Fair Value Measurements - Recon

Fair Value Measurements - Reconciliation of Changes in Fair Value of Financial Assets and Liabilities Classified as Level 3 (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy
Balance at beginning of period	$ (22)	$ 21,976	$ (28,398)
Total gain (loss) included in earnings	40,563	24,794	31,184
Settlement (gain) loss	(16,979)	(46,792)	19,190
Transfers in and/or out of Level 3	0	0	0
Balance at end of period	23,562	(22)	21,976
Change in unrealized gains (losses) relating to assets and liabilities still held at the end of the period	$ 23,562	$ (22)	$ 19,732

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - Impaired_Asset_And_Liabilty	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Number of non-financial assets and liabilities impaired	0	0	0

Fair Value Measurements - Carry

Fair Value Measurements - Carrying Amount and Fair Value of Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair value disclosures
Long-term debt	$ 1,133,924	$ 1,220,025
Current maturities	(188,000)	(87,000)
Long-term debt, excluding current maturities	945,924	1,133,025
Carrying Amount
Fair value disclosures
Long-term debt	1,133,924	1,220,025
Current maturities	(188,000)	(87,000)
Long-term debt, excluding current maturities	945,924	1,133,025
Estimated Fair Value
Fair value disclosures
Long-term debt	1,213,811	1,260,259
Current maturities	(189,332)	(88,704)
Long-term debt, excluding current maturities	$ 1,024,479	$ 1,171,555

Asset Retirement Obligations -

Asset Retirement Obligations - Activity Related to Asset Retirement Obligations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Asset Retirement Obligation
Balance at beginning of period	$ 72,098	$ 51,622
Liabilities incurred	10,008	7,646
Liabilities settled	(322)	(1,467)
Accretion expense	4,205	3,430
Change in estimate	0	10,867
Balance at end of period	85,989	72,098
Less: current asset retirement obligation	(500)	(500)
Noncurrent asset retirement obligation	$ 85,489	$ 71,598

Commitments and Contingencies -

Commitments and Contingencies - Future Minimum Obligations under Transportation and Gathering Agreements (Details) - Transportation Agreement Obligation $ in Thousands	Dec. 31, 2020USD ($)
Other Commitments [Line Items]
2021	$ 105,304
2022	191,455
2023	185,913
2024	179,772
2025	169,050
Thereafter	1,184,624
Future transportation agreement obligation	$ 2,016,118

Commitments and Contingencies_2

Commitments and Contingencies - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Operating lease cost	$ 5.4	$ 11.5
Variable lease cost	1.1	6.6
Short-term lease payments	$ 26.3	$ 267.9
Minimum
Lessee, Lease, Description [Line Items]
Remaining lease term	6 months
Maximum
Lessee, Lease, Description [Line Items]
Remaining lease term	25 years
Drilling Rigs, Fracturing and Other Equipment \| Minimum
Lessee, Lease, Description [Line Items]
Short-term lease, term	30 days
Drilling Rigs, Fracturing and Other Equipment \| Maximum
Lessee, Lease, Description [Line Items]
Short-term lease, term	1 year

Commitments and Contingencies_3

Commitments and Contingencies - Future Undiscounted Minimum Cash Payment Obligations for Operating Lease Liabilities (Details) $ in Thousands	Dec. 31, 2020USD ($)
Operating Lease Liabilities, Payments Due (Under Topic 842)
2021	$ 5,556
2022	4,894
2023	4,613
2024	4,653
2025	4,675
Thereafter	20,495
Total undiscounted future lease payments	44,886
Present value adjustment	(11,267)
Net operating lease liabilities	$ 33,619

Commitments and Contingencies_4

Commitments and Contingencies - Supplemental Cash Flow Information Related to Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Operating cash flows from operating leases	$ 5,338	$ 4,614
Investing cash flows from operating leases	$ 0	$ 6,647

Commitments and Contingencies_5

Commitments and Contingencies - Information Regarding Weighted-Average Remaining Lease Term and Weighted-Average Discount Rate for Operating Leases (Details)	Dec. 31, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Operating leases, weighted-average remaining lease term	11 years 1 month 6 days	12 years 1 month 6 days
Operating leases, weighted-average discount rate	5.00%	5.00%

Revenue Recognition - Revenues

Revenue Recognition - Revenues from Contracts with Customers Disaggregated by Product (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	$ 1,405,220	$ 1,985,469	$ 2,143,716
Natural gas
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	1,404,989	1,985,240	1,881,150
Crude oil and condensate
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	48,722
Brokered natural gas
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	209,530
Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	$ 231	$ 229	$ 4,314

Revenue Recognition - Narrative

Revenue Recognition - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Unsatisfied performance obligations	$ 8,900
Receivables from contracts with customers	$ 215.3	$ 209.2
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 \| Maximum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Unsatisfied performance obligations, expected period of satisfaction	18 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 \| Minimum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Unsatisfied performance obligations, expected period of satisfaction	3 years

Income Taxes - Summary of Incom

Income Taxes - Summary of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current
Federal	$ (31,838)	$ (29,584)	$ (95,191)
State	655	4,320	6,682
Total	(31,183)	(25,264)	(88,509)
Deferred
Federal	67,451	233,136	230,643
State	4,326	11,282	(1,040)
Total	71,777	244,418	229,603
Income tax expense	$ 40,594	$ 219,154	$ 141,094

Income Taxes - Schedule of Reco

Income Taxes - Schedule of Reconciliation of Income Tax Expense (Benefit) Computed by Applying Statutory Federal Income Tax Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Amount
Computed "expected" federal income tax	$ 50,636	$ 189,047	$ 146,609
State income tax, net of federal income tax benefit	4,486	14,773	11,850
Deferred tax adjustment related to change in overall state tax rate	1,213	(660)	(15,208)
Valuation allowance	(3,800)	17,676	8,975
Excess executive compensation	5,249	1,935	1,382
Reserve on uncertain tax positions	5,964	5	0
Uncertain tax positions	(23,216)	0	0
Tax Act	0	0	(11,367)
Other, net	62	(3,622)	(1,147)
Income tax expense	$ 40,594	$ 219,154	$ 141,094
Rate
Computed "expected" federal income tax	21.00%	21.00%	21.00%
State income tax, net of federal income tax benefit	1.86%	1.64%	1.70%
Deferred tax adjustment related to change in overall state tax rate	0.50%	(0.07%)	(2.18%)
Valuation allowance	(1.58%)	1.96%	1.29%
Excess executive compensation	2.18%	0.21%	0.20%
Reserve on uncertain tax positions	2.47%	0.00%	0.00%
Uncertain tax positions	(9.63%)	0.00%	0.00%
Tax Act	0	0	(0.0163)
Other, net	0.04%	(0.40%)	(0.16%)
Income tax expense	16.84%	24.34%	20.21%

Income Taxes - Schedule of Comp

Income Taxes - Schedule of Composition of Net Deferred Tax Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred Tax Assets
Net operating losses	$ 22,177	$ 22,360
Alternative minimum tax credits	0	22,120
Incentive compensation	16,427	17,776
Deferred compensation	5,753	5,463
Post-retirement benefits	7,482	7,847
Equity method investments	0	21,454
Leases	7,709	8,192
Capital loss carryforward	16,486	0
Other	3,267	1,336
Less: valuation allowance	(28,231)	(31,763)
Total	51,070	74,785
Deferred Tax Liabilities
Properties and equipment	809,919	768,692
Equity method investments	1,649	0
Leases	7,709	8,192
Derivative instruments	5,988	5
Total	825,265	776,889
Net deferred tax liabilities	$ 774,195	$ 702,104

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
Income Taxes - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
State tax effected net operating losses
Effective tax rate	16.84%	24.34%	20.21%
Alternative minimum tax credits	$ 0	$ 22,120
Valuation allowance on deferred tax benefits related to equity method investments	28,231	31,763
Unrecognized tax benefits	6,484	$ 520	$ 16,850	$ 663
Liability for accrued interest	600
State
State tax effected net operating losses
Net operating loss carryforwards	382,500
Valuation allowance on operating loss carryforwards	13,100
Research and development tax credits
State tax effected net operating losses
Unrecognized tax benefits	6,000
Liability for accrued interest	500
Capital loss carryforward
State tax effected net operating losses
Tax credit carryforward	72,200
Tax credit carryforwards valuation allowance	$ 14,900

Income Taxes - Schedule of Re_2

Income Taxes - Schedule of Reconciliation of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of unrecognized tax benefits
Balance at beginning of year	$ 520	$ 16,850	$ 663
Additions for tax positions of current year	499	0	0
Additions for tax positions of prior years	5,465	0	16,187
Reductions for tax positions of prior years	0	(16,330)	0
Balance at end of year	$ 6,484	$ 520	$ 16,850

Employee Benefit Plans - Narrat

Employee Benefit Plans - Narrative (Details)	12 Months Ended
Employee Benefit Plans - Narrative (Details)	Dec. 31, 2020USD ($)Retireeshares	Dec. 31, 2019USD ($)Retireeshares	Dec. 31, 2018USD ($)
Restructuring Cost and Reserve [Line Items]
Number of retirees and dependents \| Retiree	337	310
Subsidy limit percentage of expected annual fully insured premium over age threshold	60.00%
Subsidy limit percentage of expected annual fully insured premium under age threshold	$ 648,000
Annual subsidy limit percentage increases for fully insured premium over age threshold	3.50%
Estimated contributions next year	$ 2,100,000
Liabilities, including common stock	30,581,000	$ 27,012,000
Compensation (benefit) expense	$ 600,000	2,400,000	$ 3,100,000
Savings Investment Plan
Restructuring Cost and Reserve [Line Items]
Employer matching percent	6.00%
Maximum contribution, percent of employee salary	10.00%
Plan contributions charged to expense	$ 5,600,000	5,800,000	5,900,000
Deferred Compensation Plan
Restructuring Cost and Reserve [Line Items]
Market value of the trust assets, excluding common stock	22,500,000	18,400,000
Liabilities, including common stock	$ 30,600,000	$ 27,000,000
Number of common stock deferred into the rabbi trust (in shares) \| shares	495,774	495,774
Common stock held in rabbi trust	$ 5,100,000	$ 5,100,000
Contributions to deferred compensation plan	$ 1,000,000	$ 1,000,000	$ 1,100,000

Employee Benefit Plans - Change

Employee Benefit Plans - Change in Postretirement Benefit Obligation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Change in Benefit Obligation
Benefit obligation at beginning of year	$ 34,438	$ 29,777	$ 31,050
Service cost	1,493	1,533	1,776
Interest cost	974	1,283	1,172
Actuarial (gain) loss	(2,119)	3,279	(3,165)
Benefits paid	(2,042)	(1,434)	(1,056)
Benefit obligation at end of year	32,744	34,438	29,777
Change in Plan Assets
Fair value of plan assets at end of year	0	0	0
Funded status at end of year	$ (32,744)	$ (34,438)	$ (29,777)

Employee Benefit Plans - Schedu

Employee Benefit Plans - Schedule of Amounts Recognized in Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Amounts Recognized in the Balance Sheet
Current liabilities	$ 2,031	$ 1,725	$ 1,865
Non-current liabilities	30,713	32,713	27,912
Amounts recognized in the balance sheet	$ 32,744	$ 34,438	$ 29,777

Employee Benefit Plans - Amount

Employee Benefit Plans - Amount Recognized in Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Amounts Recognized in Accumulated Other Comprehensive Income
Net actuarial (gain) loss	$ (57)	$ 2,025	$ (1,253)
Prior service cost	(3,078)	(3,787)	(4,497)
Amount recognized in accumulated other comprehensive income (loss)	$ (3,135)	$ (1,762)	$ (5,750)

Employee Benefit Plans - Compon

Employee Benefit Plans - Components of Net Periodic Benefit Cost and Other Amounts Recognized in Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Components of Net Periodic Postretirement Benefit Cost
Service cost	$ 1,493	$ 1,533	$ 1,776
Interest cost	974	1,283	1,172
Amortization of prior service cost	(709)	(709)	(709)
Amortization of net loss	(36)	0	0
Net periodic postretirement cost	1,722	2,107	2,239
Other Changes in Benefit Obligations Recognized in Other Comprehensive Income (Loss)
Net (gain) loss	(2,118)	3,279	(3,165)
Amortization of prior service cost	709	709	709
Amortization of net loss	36	0	0
Total recognized in other comprehensive income	(1,373)	3,988	(2,456)
Total recognized in net periodic benefit cost (income) and other comprehensive income	$ 349	$ 6,095	$ (217)

Employee Benefit Plans - Assump

Employee Benefit Plans - Assumptions Used to Determine Projected Postretirement Benefit Obligations and Postretirement Costs (Details)	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Weighted-average assumptions used to determine projected pension benefit obligations
Discount rate	2.65%	3.50%	4.45%
Health care cost trend rate for medical benefits assumed for next year (pre-65)	6.75%	7.00%	7.25%
Health care cost trend rate for medical benefits assumed for next year (post-65)	5.00%	5.25%	5.50%
Ultimate trend rate (pre-65)	4.50%	4.50%	4.50%
Ultimate trend rate (post-65)	4.50%	4.50%	4.50%
Beginning discount rate	3.50%	4.45%	3.85%

Employee Benefit Plans - Sche_2

Employee Benefit Plans - Schedule of Estimated Benefit Payments (Details) $ in Thousands	Dec. 31, 2020USD ($)
Estimated future benefit payments
2021	$ 2,058
2022	2,085
2023	1,984
2024	1,860
2025	1,789
Years 2026 - 2030	$ 9,018

Capital Stock - Narrative (Deta

Capital Stock - Narrative (Details) - USD ($) $ in Millions	May 01, 2024	May 01, 2014	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Incentive Plans
Number of shares repurchased (in shares)			0	25,500,000	38,500,000
Cost of shares repurchased				$ 488.5	$ 904.1
Treasury stock, number of shares authorized to be repurchased (in shares)			11,000,000
Cumulative number of shares repurchased under a share repurchase program (in shares)			99,000,000
Treasury stock, cumulative shares retired (in shares)			20,000,000
Cumulative cost of shares repurchased under a share repurchase program			$ 1,900
Treasury stock reissued (in shares)			0
Shares held as treasury stock (in shares)			78,957,318	78,957,318
2014 Incentive Plan
Incentive Plans
Number of shares reserved for issuance (in shares)		18,000,000
Number of shares available for issuance (in shares)			11,100,000
2014 Incentive Plan \| Stock Options \| Maximum
Incentive Plans
Number of shares reserved for issuance (in shares)		10,000,000
2004 Incentive Plan
Incentive Plans
Additional awards granted (in shares)		0
Scenario Forecast \| 2014 Incentive Plan
Incentive Plans
Additional awards granted (in shares)	0

Stock-Based Compensation - Narr

Stock-Based Compensation - Narrative (Details)	1 Months Ended	12 Months Ended
Stock-Based Compensation - Narrative (Details)	Feb. 28, 2021USD ($)performance_criteriashares	Dec. 31, 2020USD ($)Award_Typeshares	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense		$ 43,200,000	$ 30,800,000	$ 33,100,000
Tax benefit for share-based compensation expense		10,000,000	7,000,000	7,600,000
Defined contribution cost recognized		$ 600,000
Deferred Compensation, Share-based Payments
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares held in employee trust earned but not distributed (in shares) \| shares		495,774
Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense		$ 400,000	1,300,000	2,800,000
Award vesting period		3 years
Compensation cost not yet recognized		$ 700,000
Period of recognition for unrecognized compensation costs		1 year 4 months 24 days
Fair value of award		$ 200,000	4,100,000	200,000
Aggregate intrinsic value		$ 800,000
Weighted-average remaining contractual term of non-vested shares		1 year 4 months 24 days
Restricted Stock Awards \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected forfeiture rate		5.00%
Restricted Stock Awards \| Graduated or Graded Vesting \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		3 years
Restricted Stock Awards \| Graduated or Graded Vesting \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		4 years
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense		$ 2,100,000	2,100,000	1,900,000
Aggregate intrinsic value		11,500,000
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense		$ 39,600,000	$ 28,800,000	$ 30,600,000
Award vesting period		3 years
Compensation cost not yet recognized		$ 28,000,000
Period of recognition for unrecognized compensation costs		2 years 2 months 12 days
Number of performance award types \| Award_Type		3
Aggregate intrinsic value		$ 63,700,000
Weighted-average remaining contractual term of non-vested shares		1 year 4 months 24 days
Number of performance awards where the performance period has ended \| Award_Type		2
Performance Shares \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected forfeiture rate		0.00%
Performance Shares \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected forfeiture rate		7.00%
Internal Metrics Performance Share Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of performance award types \| Award_Type		2
Rights to share portion of award, maximum percent		100.00%
Market Based Performance Share Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of performance award types \| Award_Type		1
Rights to share portion of award, maximum percent		100.00%
Rights to cash portion of award, maximum percent		100.00%
Employee Performance Share Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		3 years
Minimum operating cash flow for performance based award		$ 100,000,000
Employee Performance Share Awards \| Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of performance criteria \| performance_criteria	3
Number of performance awards issued and certified (in shares) \| shares	481,784
Grant date fair value of performance shares issued and certified	$ 11,200,000
Employee Performance Share Awards \| 50% Vesting on Third Anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Rights to share portion of award, maximum percent		100.00%	33.00%	33.00%
Hybrid Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Minimum operating cash flow for performance based award		$ 100,000,000
Hybrid Performance Shares \| Graduated or Graded Vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		3 years
Hybrid Performance Shares \| 25% Vesting on First and Second Anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage		25.00%
Hybrid Performance Shares \| 50% Vesting on Third Anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage		50.00%
TSR Performance Share Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period of peer group		3 years
Cash payments for share-based compensation		$ 14,000,000	$ 5,000,000	$ 3,300,000
Number of performance awards issued and certified (in shares) \| shares		482,581
Grant date fair value of performance shares issued and certified		$ 9,600,000
Payments for stock-based compensation		7,900,000
TSR Performance Share Awards \| Liability
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Current portion of share-based liability		0	6,100,000
Noncurrent portion of share-based liability		$ 6,800,000	$ 4,100,000

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Restricted Stock Award Activity (Details) - Restricted Stock Awards - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Shares
Outstanding at beginning of period (in shares)	58,834	150,293	161,450
Granted (in shares)	0	55,500	0
Vested (in shares)	(6,334)	(143,959)	(7,157)
Forfeited (in shares)	(2,000)	(3,000)	(4,000)
Outstanding at end of period (in shares)	50,500	58,834	150,293
Weighted- Average Grant Date Fair Value per Share
Outstanding at beginning of period (in dollars per share)	$ 25.19	$ 28.12	$ 28
Granted (in dollars per share)	0	25.29	0
Vested (in dollars per share)	24.39	28.29	25.17
Forfeited (in dollars per share)	25.29	25.29	28.45
Outstanding at end of period (in dollars per share)	$ 25.29	$ 25.19	$ 28.12
Additional disclosures
Aggregate intrinsic value	$ 0.8
Weighted-average remaining contractual term of non-vested shares	1 year 4 months 24 days

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Restricted Stock Unit Activity (Details) - Restricted Stock Units - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Shares
Outstanding at beginning of period (in shares)	574,219	490,415	407,563
Granted and fully vested (in shares)	130,065	83,804	82,852
Issued (in shares)	0	0	0
Forfeited (in shares)	0	0	0
Outstanding at end of period (in shares)	704,284	574,219	490,415
Weighted- Average Grant Date Fair Value per Share
Outstanding at beginning of period (in dollars per share)	$ 18.47	$ 17.41	$ 16.17
Granted and fully vested (in dollars per share)	15.88	24.70	23.47
Issued (in dollars per share)	0	0	0
Forfeited (in dollars per share)	0	0	0
Outstanding at end of period (in dollars per share)	$ 17.99	$ 18.47	$ 17.41
Additional disclosures
Aggregate intrinsic value	$ 11.5

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Performance Share Awards Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Employee Performance Share Awards
Shares
Outstanding at beginning of period (in shares)	1,259,287	1,280,021	1,095,970
Granted (in shares)	722,500	526,730	531,670
Issued and fully vested (in shares)	(334,640)	(388,370)	(315,970)
Forfeited (in shares)	(37,023)	(159,094)	(31,649)
Outstanding at end of period (in shares)	1,610,124	1,259,287	1,280,021
Weighted- Average Grant Date Fair Value per Share
Outstanding at beginning of period (in dollars per share)	$ 23.64	$ 22.22	$ 23.31
Granted (in dollars per share)	15.60	24.95	23.25
Issued and fully vested (in dollars per share)	22.60	20.49	27.71
Forfeited (in dollars per share)	20.38	24.29	22.33
Outstanding at end of period (in dollars per share)	$ 20.31	$ 23.64	$ 22.22
Hybrid Performance Shares
Shares
Outstanding at beginning of period (in shares)	692,788	662,388	574,354
Granted (in shares)	506,412	315,029	321,720
Issued and fully vested (in shares)	(295,649)	(284,629)	(233,686)
Forfeited (in shares)	0	0	0
Outstanding at end of period (in shares)	903,551	692,788	662,388
Weighted- Average Grant Date Fair Value per Share
Outstanding at beginning of period (in dollars per share)	$ 23.90	$ 22.48	$ 22.72
Granted (in dollars per share)	15.60	24.95	23.25
Issued and fully vested (in dollars per share)	23.40	21.78	24.12
Forfeited (in dollars per share)	0	0	0
Outstanding at end of period (in dollars per share)	$ 19.41	$ 23.90	$ 22.48
TSR Performance Share Awards
Shares
Outstanding at beginning of period (in shares)	1,428,634	1,299,868	1,109,708
Granted (in shares)	862,180	536,673	482,581
Issued and fully vested (in shares)	(891,961)	(407,907)	(292,421)
Forfeited (in shares)	0	0	0
Outstanding at end of period (in shares)	1,398,853	1,428,634	1,299,868
Weighted- Average Grant Date Fair Value per Share
Outstanding at beginning of period (in dollars per share)	$ 20.17	$ 19.47	$ 19.23
Granted (in dollars per share)	13.79	20.63	19.92
Issued and fully vested (in dollars per share)	19.89	18.57	19.29
Forfeited (in dollars per share)	0	0	0
Outstanding at end of period (in dollars per share)	$ 16.41	$ 20.17	$ 19.47

Stock-Based Compensation - Assu

Stock-Based Compensation - Assumptions Used to Determine Grant Date Fair Value of Equity and Liability Component (Details) - TSR Performance Share Awards - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stockholders' Equity
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value per performance share award granted during the period	$ 13.79	$ 20.63	$ 19.92
Stock price volatility	29.50%	31.30%	37.30%
Risk free rate of return	1.40%	2.50%	2.40%
Liability
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock price volatility, minimum rate	42.40%	29.80%	29.90%
Stock price volatility, maximum rate	52.40%	30.40%	31.10%
Risk free rate of return	10.00%	160.00%
Risk free rate of return, minimum rate			2.50%
Risk free rate of return, maximum rate			2.60%
Minimum \| Liability
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value per performance share award granted during the period	$ 10.37	$ 6.18	$ 15.15
Maximum \| Liability
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value per performance share award granted during the period	$ 10.81	$ 14.80	$ 20.12

Earnings per Common Share - Cal

Earnings per Common Share - Calculation of Basic and Diluted Weighted-Average Shares Outstanding (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Weighted-average shares - basic (in shares)	398,521	415,514	445,538
Dilution effect of stock awards at end of period (in shares)	2,001	1,937	2,030
Weighted-average shares - diluted (in shares)	400,522	417,451	447,568

Earnings per Common Share - C_2

Earnings per Common Share - Calculation of Weighted-Average Shares Excluded from Diluted EPS Due to Anti-Dilutive Effect (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock Compensation Plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average stock awards excluded from diluted EPS due to the anti-dilutive effect calculated using the treasury stock method (in shares)	2	669	3

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income - Changes in Accumulated Other Comprehensive Income by Component, Net of Tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Changes in accumulated other comprehensive income (loss) by component, net of tax
Balance at beginning of period	$ 2,151,487	$ 2,088,159	$ 2,523,905
Total other comprehensive income	1,059	(3,077)	2,360
Balance at end of period	2,215,707	2,151,487	2,088,159
Postretirement Benefits
Changes in accumulated other comprehensive income (loss) by component, net of tax
Balance at beginning of period	1,360	4,437	2,077
Other comprehensive income before reclassifications	1,634	(2,530)	2,461
Amounts reclassified from accumulated other comprehensive loss	(575)	(547)	(101)
Total other comprehensive income	1,059	(3,077)	2,360
Balance at end of period	$ 2,419	$ 1,360	$ 4,437

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Income - Schedule of Amounts Reclassified from Accumulated Other Comprehensive Income into Consolidated Statement of Operations (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Line items in income statement impacted by reclassifications out of accumulated other comprehensive income
General and administrative										$ 105,391	$ 94,870	$ 96,641
Amortization of net (gain) loss	[1]									28	0	0
Income before income taxes										241,123	900,224	698,137
Income tax expense										(40,594)	(219,154)	$ (141,094)
Accounting Standards Update [Extensible List]												us-gaap:AccountingStandardsUpdate201802Member
Net income		$ 131,206	$ (14,961)	$ 30,374	$ 53,910	$ 146,940	$ 90,358	$ 181,009	$ 262,763	200,529	681,070	$ 557,043
Reclassification out of Accumulated Other Comprehensive Income
Line items in income statement impacted by reclassifications out of accumulated other comprehensive income
Amortization of net (gain) loss										36	0	0
Amortization of prior service cost \| Reclassification out of Accumulated Other Comprehensive Income
Line items in income statement impacted by reclassifications out of accumulated other comprehensive income
General and administrative										709	709	709
Postretirement Benefits \| Reclassification out of Accumulated Other Comprehensive Income
Line items in income statement impacted by reclassifications out of accumulated other comprehensive income
Income before income taxes										745	709	709
Income tax expense										(170)	(162)	(162)
Cumulative effect of adoption of ASU 2018-02 reclassified to retained earnings										0	0	(446)
Net income										$ 575	$ 547	$ 101

[1]	Net of income taxes of $8 for the year ended December 31, 2020.

Additional Balance Sheet Info_3

Additional Balance Sheet Information - Certain Balance Sheet Amounts (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounts receivable, net
Trade accounts	$ 215,301	$ 209,200
Other accounts	462	1,007
Receivables gross current	215,763	210,207
Allowance for doubtful accounts	(1,039)	(1,184)
Accounts receivable, net	214,724	209,023
Other assets
Deferred compensation plan	22,510	18,381
Debt issuance cost	6,875	8,938
Operating Lease, Right-of-Use Asset	$ 33,741	$ 35,916
Operating Lease, Right-of-Use Asset [Extensible List]	us-gaap:OtherAssets	us-gaap:OtherAssets
Other accounts	$ 85	$ 56
Other assets	63,211	63,291
Accounts payable
Trade accounts	12,896	21,663
Royalty and other owners	37,243	36,191
Accrued transportation	52,238	55,586
Accrued capital costs	37,872	40,337
Taxes other than income	13,736	16,971
Other accounts	8,096	19,063
Accounts payable current	162,081	189,811
Accrued liabilities
Employee benefits	14,270	22,727
Taxes other than income	3,026	3,850
Operating lease liabilities	$ 3,991	$ 3,124
Operating Lease, Liability, Current [Extensible List]	us-gaap:AccountsPayableAndAccruedLiabilitiesCurrent	us-gaap:AccountsPayableAndAccruedLiabilitiesCurrent
Other accounts	$ 1,087	$ 1,589
Accrued liabilities	22,374	31,290
Other liabilities
Deferred compensation plan	30,581	27,012
Operating lease liabilities	$ 29,628	$ 32,677
Operating Lease, Liability, Noncurrent [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent	us-gaap:OtherLiabilitiesNoncurrent
Other accounts	$ 21,069	$ 8,595
Other liabilities	$ 81,278	$ 68,284

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information - Summary of Cash Paid for Interest and Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash paid for interest and income taxes
Interest	$ 57,043	$ 57,475	$ 80,069
Income taxes	10,964	7,808	4,635
Cash and cash equivalents	140,113	200,227
Restricted cash	11,578	13,556
Total	$ 151,691	$ 213,783	$ 2,287	$ 480,047

SUPPLEMENTAL OIL AND GAS INFO_3

SUPPLEMENTAL OIL AND GAS INFORMATION (UNAUDITED) (Details) Mcf in Thousands, MBbls in Thousands, Bcfe in Thousands, Bcf in Thousands	1 Months Ended		12 Months Ended
	Jul. 31, 2018MMBTU	Feb. 28, 2018MMBTU	Dec. 31, 2020BcfeBcfMBblsMcf	Dec. 31, 2019BcfeBcfMBbls	Dec. 31, 2018BcfeBcfMBbls	Dec. 31, 2017BcfeBcf
Proved Developed and Undeveloped Reserve (Energy) [Roll Forward]
Beginning balance			12,903	11,605	9,726
Revision of prior estimates(3)			(347)	47	780
Extensions, discoveries and other additions(4)			1,974	2,116	2,244
Production			(858)	(865)	(735)
Sales of reserves in place	(6,000)	(404,000)		0	(410)
Ending balance			13,672	12,903	11,605
Proved Developed Reserves			8,608	8,056	7,403	6,187
Proved Undeveloped Reserves			5,064	4,847	4,202	3,539
Volume ratio \| Mcf			6
Proved Undeveloped Reserves Reclassification
Proved Developed and Undeveloped Reserve (Energy) [Roll Forward]
Revision of prior estimates(3)			(66)	(18)	(345)
Performance Revision
Proved Developed and Undeveloped Reserve (Energy) [Roll Forward]
Revision of prior estimates(3)				67
Performance Revisions And Drilling
Proved Developed and Undeveloped Reserve (Energy) [Roll Forward]
Revision of prior estimates(3)			123	417
Certain Proved Developed Producing Properties
Proved Developed and Undeveloped Reserve (Energy) [Roll Forward]
Revision of prior estimates(3)			(368)	(350)
Pennsylvania
Proved Developed and Undeveloped Reserve (Energy) [Roll Forward]
Revision of prior estimates(3)					1,123
Extensions, discoveries and other additions(4)			1,974	2,116	2,243
Natural Gas
Proved Developed and Undeveloped Reserves [Roll Forward]
Beginning balance \| Bcf			12,903	11,604	9,353
Revision of prior estimates(3) \| Bcf			(347)	48	776
Extensions, discoveries and other additions(4) \| Bcf			1,974	2,116	2,243
Production \| Bcf			(858)	(865)	(730)
Sales of reserves in place(5) \| Bcf				0	(38)
Ending balance \| Bcf			13,672	12,903	11,604
Proved Developed Reserves \| Bcf			8,608	8,056	7,402	6,001
Proved Undeveloped Reserves \| Bcf			5,064	4,847	4,202	3,352
Crude Oil and Natural Gas Liquids (NGL)
Proved Developed and Undeveloped Reserves [Roll Forward]
Beginning balance \| MBbls			22	120	62,252
Revision of prior estimates(3) \| MBbls			(3)	(48)	677
Extensions, discoveries and other additions(4) \| MBbls			0	0	0
Production \| MBbls			(4)	0	(829)
Sales of reserves in place(5) \| MBbls				(50)	(61,980)
Ending balance \| MBbls			15	22	120
Proved Developed Reserves \| Bcf			15	22	107	31,066
Proved Undeveloped Reserves \| Bcf			0	0	13	31,186
Proved Developed and Undeveloped Reserve (Energy) [Roll Forward]
Percentage of reserves						13.70%
Natural Gas Liquids
Proved Developed and Undeveloped Reserve (Energy) [Roll Forward]
Percentage of reserves						1.00%

SUPPLEMENTAL OIL AND GAS INFO_4

SUPPLEMENTAL OIL AND GAS INFORMATION (UNAUDITED) - Capitalized Costs (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Extractive Industries [Abstract]
Aggregate capitalized costs relating to oil and gas producing activities	$ 7,154,452	$ 6,676,122	$ 5,995,194
Aggregate accumulated depreciation, depletion and amortization	(3,148,564)	(2,861,014)	(2,540,068)
Net capitalized costs	$ 4,005,888	$ 3,815,108	$ 3,455,126

SUPPLEMENTAL OIL AND GAS INFO_5

SUPPLEMENTAL OIL AND GAS INFORMATION (UNAUDITED) - Costs Incurred (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Extractive Industries [Abstract]
Property acquisition costs, proved	$ 0	$ 0	$ 0
Property acquisition costs, unproved	5,821	6,072	29,851
Exploration costs	15,419	20,270	94,309
Development costs	546,646	761,326	778,574
Total costs	$ 567,886	$ 787,668	$ 902,734

SUPPLEMENTAL OIL AND GAS INFO_6

SUPPLEMENTAL OIL AND GAS INFORMATION (UNAUDITED) - Average Prices (Details)	12 Months Ended
	Dec. 31, 2020$ / bbl$ / Mcf	Dec. 31, 2019$ / bbl$ / Mcf	Dec. 31, 2018$ / bbl$ / Mcf
Natural Gas
Oil and Gas, Average Sale Price and Production Cost Per Unit [Line Items]
Average sales price \| $ / Mcf	1.64	2.35	2.58
Crude Oil
Oil and Gas, Average Sale Price and Production Cost Per Unit [Line Items]
Average sales price	32.53	55.80	65.21
Natural Gas Liquids
Oil and Gas, Average Sale Price and Production Cost Per Unit [Line Items]
Average sales price	0	0	21.64

SUPPLEMENTAL OIL AND GAS INFO_7

SUPPLEMENTAL OIL AND GAS INFORMATION (UNAUDITED) - Standardized Measure (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Extractive Industries [Abstract]
Future cash inflows	$ 22,385,385	$ 30,302,480	$ 29,904,474
Future production costs	(10,783,895)	(10,039,294)	(8,702,734)
Future development costs(1)	(1,612,659)	(2,006,167)	(1,766,796)
Future income tax expenses	(2,175,916)	(4,042,787)	(4,166,089)
Future net cash flows	7,812,915	14,214,232	15,268,855
10% annual discount for estimated timing of cash flows	(4,750,760)	(8,353,115)	(8,785,547)
Standardized measure of discounted future net cash flows	3,062,155	5,861,117	6,483,308	$ 5,010,446
Abandonment costs	$ 223,700	$ 212,900	$ 193,500

SUPPLEMENTAL OIL AND GAS INFO_8

SUPPLEMENTAL OIL AND GAS INFORMATION (UNAUDITED) - Change In Standardized Measure (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Increase (Decrease) in Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Roll Forward]
Beginning balance	$ 5,861,117	$ 6,483,308	$ 5,010,446
Discoveries and extensions, net of related future costs	311,336	1,075,839	1,280,499
Net changes in prices and production costs	(4,326,254)	(1,510,104)	2,078,479
Accretion of discount	750,041	813,480	596,569
Revisions of previous quantity estimates	(107,467)	28,310	586,494
Timing and other	5,992	(192,563)	(76,761)
Development costs incurred	501,093	468,748	338,297
Sales and transfers, net of production costs	(746,310)	(1,316,752)	(1,343,872)
Sales of reserves in place	0	(1,350)	(1,290,594)
Net change in income taxes	812,607	12,201	(696,249)
Ending balance	$ 3,062,155	$ 5,861,117	$ 6,483,308

QUARTERLY FINANCIAL INFORMATI_3

QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended								12 Months Ended
	Nov. 30, 2019	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effect of Fourth Quarter Events [Line Items]
Revenues		$ 456,778	$ 291,041	$ 332,348	$ 386,457	$ 461,368	$ 429,111	$ 534,117	$ 641,681	$ 1,466,624	$ 2,066,277	$ 2,188,148
(Loss) earnings on equity method investments						69,302	3,860	3,650	3,684	(59)	80,496	1,137
Operating Income (Loss)		162,892	(7,533)	53,716	86,401	222,209	129,777	250,805	352,959	295,476	955,750	771,801
Net income		$ 131,206	$ (14,961)	$ 30,374	$ 53,910	$ 146,940	$ 90,358	$ 181,009	$ 262,763	$ 200,529	$ 681,070	$ 557,043
Basic (in dollars per share)		$ 0.33	$ (0.04)	$ 0.08	$ 0.14	$ 0.36	$ 0.22	$ 0.43	$ 0.62	$ 0.50	$ 1.64	$ 1.25
Diluted (in dollars per share)		$ 0.33	$ (0.04)	$ 0.08	$ 0.13	$ 0.36	$ 0.22	$ 0.43	$ 0.62	$ 0.50	$ 1.63	$ 1.24
Meade
Effect of Fourth Quarter Events [Line Items]
(Loss) earnings on equity method investments										$ (24)	$ 90,621	$ 2,369
Gain on Sale of Investments	$ (75,800)